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These pages contain a collection of guides, tutorials, and shortcuts for the software I use.

Firefox Shortcuts

• Navigation
• Current Page
• Editing
• Search
• Windows & Tabs
• History
• Bookmarks
• Tools
• PDF Viewer
• Miscellaneous
• Media shortcuts
• Selection of Multiple Tabs
• Developer shortcuts

Navigation

Current Page

Editing

Search

Windows & Tabs

See also Use tabs to organize lots of websites in a single window.

History

Bookmarks

Tools

PDF Viewer

Miscellaneous

Media shortcuts

See also HTML5 audio and video in Firefox and the list of Picture-in-Picture (PiP) shortcuts.

Selection of Multiple Tabs

These shortcuts require the tab bar to be “in focus”. Currently, the only way to do this is to focus an adjacent object and “tab into” the tab bar, for instance, by hitting Ctrl + L to focus the address bar, and then Shift + Tab repeatedly until the current tab gets a colored border.

Developer shortcuts

You can also use keyboard shortcuts with developer tools in Firefox. See the All keyboard shortcuts Firefox Source Docs page.

Chrome Shortcuts

• Windows & Linux
• Open the menu for tab groups
• Move, collapse and expand tab groups
• Google Chrome feature shortcuts
• Address bar shortcuts
• Webpage shortcuts
• Mouse shortcuts

Windows & Linux

Tab & window shortcuts

Open the menu for tab groups

1. On your Windows computer, open Chrome.
2. To move to tab selection, press F6 until your tabs are in focus.
3. To switch focus to a specific tab, press Tab to move forward or Shift + Tab to move backward.
4. To open the tab group menu, press Menu.
5. To make a menu selection:
   • To move up or down, press Up arrow or Down arrow .
   • To move left or right, press Left arrow or Right arrow .
   • To select a menu option, press Enter.

Move, collapse and expand tab groups

You can collapse a tab group so that only the group name or a colored circle shows. You can also expand a tab group so that all tabs show.

To collapse or expand a tab group:

1. Switch focus to the tab group header.
2. Press Space bar or Enter.

Tip: When a tab group is collapsed, you can only select the group. You can't select individual tabs inside the group.

To move a tab or tab group:

1. Switch focus to the tab or tab group.
2. Press Ctrl + Left arrow or Ctrl + Right arrow .

Google Chrome feature shortcuts

Address bar shortcuts

Use the following shortcuts in the address bar:

Webpage shortcuts

Mouse shortcuts

The following shortcuts require you to use your mouse:

Action	Shortcut
Open a link in a current tab (mouse only)	Drag a link to a tab
Open a link in new background tab	Ctrl + Click a link
Open a link, and jump to it	Ctrl + Shift + Click a link
Open a link, and jump to it (mouse only)	Drag a link to a blank area of the tab strip
Open a link in a new window	Shift + Click a link
Open a tab in a new window (mouse only)	Drag the tab out of the tab strip
Move a tab to a current window (mouse only)	Drag the tab into an existing window
Return a tab to its original position	Press Esc while dragging
Save the current webpage as a bookmark	Drag the web address to the Bookmarks Bar
Scroll horizontally on the page	Shift + Scroll your mousewheel
Download the target of a link	Alt + Click a link
Display your browsing history	Right-click Back or click & hold Back Right-click Next or click & hold Next
Switch between maximized and windowed modes	Double-click a blank area of the tab strip
Make everything on the page bigger	Ctrl + Scroll your mousewheel up
Make everything on the page smaller	Ctrl + Scroll your mousewheel down

Cisco Router & Switch Configuration

• Part 1: Configuring a Cisco Router
  • 1. Access the Router CLI
  • 2. Enter Privileged EXEC Mode
  • 3. Enter Global Configuration Mode
  • 4. Basic Router Configuration
  • 5. Configure Router Interfaces (Assign IP Addresses)
  • 6. Configure a Default Route (for Internet Access)
  • 7. Save the Configuration
  • 8. Verify Configuration (from Privileged EXEC mode #)
• Part 2: Configuring a Cisco Switch
  • 1. Access the Switch CLI
  • 2. Enter Privileged EXEC Mode
  • 3. Enter Global Configuration Mode
  • 4. Basic Switch Configuration (Similar to Router)
  • 5. Configure VLANs (Virtual Local Area Networks)
  • 6. Assign Access Ports to VLANs
  • 7. Configure Trunk Ports (for inter-VLAN communication between switches/routers)
  • 8. Configure a Management IP Address (Switched Virtual Interface - SVI)
  • 9. Configure a Default Gateway (for management to reach other subnets)
  • 10. Save the Configuration
  • 11. Verify Configuration (from Privileged EXEC mode #)

Part 1: Configuring a Cisco Router

Routers operate at Layer 3 (Network Layer) and are responsible for forwarding packets between different networks (IP subnets).

Assumptions:

• You have a Cisco router (physical or in Packet Tracer/GNS3).
• You have a console cable connected from your PC's serial port (or USB-to-serial adapter) to the router's console port.
• You are using a terminal emulation program (like PuTTY, Tera Term, or Packet Tracer's Terminal app) with settings typically 9600 baud, 8 data bits, no parity, 1 stop bit, no flow control.

1. Access the Router CLI

• Power on the router.
• Open your terminal emulation program and connect to the console port.
• You'll likely see a boot-up sequence. If it asks "Would you like to enter the initial configuration dialog? [yes/no]:", type no and press Enter.
• You'll arrive at the User EXEC mode: Router>

2. Enter Privileged EXEC Mode

• From Router>, type enable or en.
• Press Enter.
• The prompt changes to Router#. This mode allows you to view system information and enter global configuration mode.

3. Enter Global Configuration Mode

• From Router#, type configure terminal or conf t.
• Press Enter.
• The prompt changes to Router(config)#. This mode allows you to make system-wide changes.

4. Basic Router Configuration

• Set a Hostname:

  Router(config)# hostname MyBranchRouter
  MyBranchRouter(config)#
  

  (The prompt changes immediately)

• Secure Privileged EXEC Mode (Encrypts password):

  MyBranchRouter(config)# enable secret YourStrongPassword
  

  (This password will be requested when typing enable)

• Secure Console Line (Local Login for Console):

  MyBranchRouter(config)# line console 0
  MyBranchRouter(config-line)# password ConsolePass
  MyBranchRouter(config-line)# login
  MyBranchRouter(config-line)# exit
  

  (This password will be requested when connecting via console)

• Secure VTY Lines (for Telnet/SSH access): VTY lines allow remote access. A common range is 0 4 (allowing 5 simultaneous sessions).

  MyBranchRouter(config)# line vty 0 4
  MyBranchRouter(config-line)# password VTYPass
  MyBranchRouter(config-line)# login
  MyBranchRouter(config-line)# exit
  

  (These passwords will be requested when connecting via Telnet/SSH)

• Encrypt all plaintext passwords:

  MyBranchRouter(config)# service password-encryption
  

  (This encrypts passwords set using password command, not enable secret which is already hashed)

• Set a Banner (Message of the Day):

  MyBranchRouter(config)# banner motd # Unauthorized access is prohibited #
  

  (The # is a delimiter; you can use any character not in the message)

5. Configure Router Interfaces (Assign IP Addresses)

Routers have physical interfaces (e.g., GigabitEthernet, FastEthernet, Serial). Each interface usually connects to a different network segment.

• Identify Interfaces: In Privileged EXEC mode (MyBranchRouter#), you can use:

  show ip interface brief
  

  This shows all interfaces, their IP addresses (if any), and their status.

• Enter Interface Configuration Mode:

  MyBranchRouter(config)# interface GigabitEthernet0/0  (or FastEthernet0/0, or Serial0/0/0 etc.)
  MyBranchRouter(config-if)#
  

• Assign IP Address and Subnet Mask:

  MyBranchRouter(config-if)# ip address 192.168.1.1 255.255.255.0
  

• Activate the Interface: By default, interfaces are administratively down.

  MyBranchRouter(config-if)# no shutdown
  

  (You should see a message about the interface changing state to up)

• Exit Interface Mode:

  MyBranchRouter(config-if)# exit
  MyBranchRouter(config)#
  

  (Repeat for all interfaces you need to configure)

6. Configure a Default Route (for Internet Access)

If your router connects to the internet (or another router that leads to the internet), you'll need a default route. This tells the router where to send packets if it doesn't have a specific route for the destination network.

• 0.0.0.0 0.0.0.0 represents "any network, any subnet mask."

• 10.0.0.1 would be the IP address of the "next-hop" router (e.g., your ISP's router or your main home router).

  MyBranchRouter(config)# ip route 0.0.0.0 0.0.0.0 10.0.0.1
  

7. Save the Configuration

Changes made in config modes are only in the running-configuration (RAM). To save them permanently so they survive a reboot, you need to copy them to startup-configuration (NVRAM).

• From MyBranchRouter(config)#, type exit to go back to Privileged EXEC mode.

  MyBranchRouter(config)# exit
  MyBranchRouter#
  

• Save the configuration:

  MyBranchRouter# copy running-config startup-config
  Destination filename [startup-config]? (Press Enter)
  Building configuration...
  

8. Verify Configuration (from Privileged EXEC mode #)

• show running-config: Shows the current active configuration in RAM.
• show ip interface brief: Shows a summary of all interfaces, their IP addresses, and status.
• show ip route: Shows the routing table.
• ping <destination_ip>: Test connectivity (e.g., ping 192.168.1.254).

Part 2: Configuring a Cisco Switch

Switches primarily operate at Layer 2 (Data Link Layer) and are responsible for forwarding frames within the same local network (LAN) based on MAC addresses.

Assumptions:

• You have a Cisco switch (physical or in Packet Tracer/GNS3).
• You have a console cable connected from your PC's serial port to the switch's console port.
• You are using a terminal emulation program (like PuTTY, Tera Term, or Packet Tracer's Terminal app).

1. Access the Switch CLI

• Power on the switch.
• Open your terminal emulation program and connect to the console port.
• You'll likely see a boot-up sequence.
• You'll arrive at the User EXEC mode: Switch>

2. Enter Privileged EXEC Mode

• From Switch>, type enable or en.
• Press Enter.
• The prompt changes to Switch#.

3. Enter Global Configuration Mode

• From Switch#, type configure terminal or conf t.
• Press Enter.
• The prompt changes to Switch(config)#.

4. Basic Switch Configuration (Similar to Router)

• Set a Hostname:

  Switch(config)# hostname MyFloorSwitch
  MyFloorSwitch(config)#
  

• Secure Privileged EXEC Mode:

  MyFloorSwitch(config)# enable secret YourStrongPassword
  

• Secure Console Line:

  MyFloorSwitch(config)# line console 0
  MyFloorSwitch(config-line)# password ConsolePass
  MyFloorSwitch(config-line)# login
  MyFloorSwitch(config-line)# exit
  

• Secure VTY Lines (for Telnet/SSH access):

  MyFloorSwitch(config)# line vty 0 15  (Switches typically have more VTY lines than routers, up to 16)
  MyFloorSwitch(config-line)# password VTYPass
  MyFloorSwitch(config-line)# login
  MyFloorSwitch(config-line)# exit
  

• Encrypt all plaintext passwords:

  MyFloorSwitch(config)# service password-encryption
  

• Set a Banner:

  MyFloorSwitch(config)# banner motd # Authorized access only #
  

5. Configure VLANs (Virtual Local Area Networks)

VLANs segment a broadcast domain. By default, all ports are in VLAN 1.

• Create a new VLAN:

  MyFloorSwitch(config)# vlan 10
  MyFloorSwitch(config-vlan)# name Sales_VLAN
  MyFloorSwitch(config-vlan)# exit
  

  (Repeat for other VLANs as needed, e.g., vlan 20 name IT_VLAN)

6. Assign Access Ports to VLANs

Access ports carry traffic for a single VLAN.

• Enter Interface Configuration Mode for the port:

  MyFloorSwitch(config)# interface FastEthernet0/1 (or GigabitEthernet0/1 etc.)
  MyFloorSwitch(config-if)#
  

• Set port mode to access:

  MyFloorSwitch(config-if)# switchport mode access
  

• Assign the port to a VLAN:

  MyFloorSwitch(config-if)# switchport access vlan 10
  MyFloorSwitch(config-if)# exit
  

  (Repeat for all access ports)

7. Configure Trunk Ports (for inter-VLAN communication between switches/routers)

Trunk ports carry traffic for multiple VLANs, typically connecting switches to other switches or to routers (for inter-VLAN routing).

• Enter Interface Configuration Mode for the trunk port:

  MyFloorSwitch(config)# interface GigabitEthernet0/1  (Commonly use GigE for trunks)
  MyFloorSwitch(config-if)#
  

• Set encapsulation type (usually Dot1Q):

  MyFloorSwitch(config-if)# switchport trunk encapsulation dot1q
  

• Set port mode to trunk:

  MyFloorSwitch(config-if)# switchport mode trunk
  

• Allow specific VLANs on the trunk (optional, good practice):

  MyFloorSwitch(config-if)# switchport trunk allowed vlan 1,10,20
  

  (VLAN 1 is the default and usually remains allowed)

• Exit Interface Mode:

  MyFloorSwitch(config-if)# exit
  

8. Configure a Management IP Address (Switched Virtual Interface - SVI)

Switches are Layer 2 devices, but for remote management (Telnet/SSH) they need an IP address. This is done by creating a Switched Virtual Interface (SVI) for a VLAN.

• Enter Interface VLAN mode:

  MyFloorSwitch(config)# interface vlan 1  (VLAN 1 is the default management VLAN)
  MyFloorSwitch(config-if)#
  

• Assign IP Address and Subnet Mask:

  MyFloorSwitch(config-if)# ip address 192.168.1.254 255.255.255.0
  

• Activate the Interface:

  MyFloorSwitch(config-if)# no shutdown
  

  (You should see a message about the interface changing state to up)

• Exit Interface Mode:

  MyFloorSwitch(config-if)# exit
  

9. Configure a Default Gateway (for management to reach other subnets)

For the switch to be managed from another network (e.g., from a PC on a different VLAN or the internet), it needs a default gateway (the IP address of the router connected to that VLAN).

•   MyFloorSwitch(config)# ip default-gateway 192.168.1.1
  

10. Save the Configuration

• From MyFloorSwitch(config)#, type exit to go back to Privileged EXEC mode.

  MyFloorSwitch(config)# exit
  MyFloorSwitch#
  

• Save the configuration:

  MyFloorSwitch# copy running-config startup-config
  Destination filename [startup-config]? (Press Enter)
  Building configuration...
  

11. Verify Configuration (from Privileged EXEC mode #)

• show running-config: Shows the current active configuration in RAM.
• show ip interface brief: Shows a summary of VLAN interfaces and their IP addresses.
• show vlan brief: Shows a summary of all VLANs and port assignments.
• show mac address-table: Shows the MAC address table.
• ping <ip_address>: Test connectivity (e.g., ping 192.168.1.1).

Common Cisco IOS Commands for Routers and Switches

• Navigation and Basic System Commands
• Basic Device Configuration
• Interface Configuration
• VLANs (Switches Only)
• Routing (Routers Primarily)
  • Static Routing
  • OSPF (Open Shortest Path First)
  • EIGRP (Enhanced Interior Gateway Routing Protocol)
• Security
  • Access Control Lists (ACLs)
  • Port Security (Switches Only)
  • SSH Configuration
• Monitoring and Verification (Show Commands)
• Troubleshooting Commands
• Configuration Management

This list covers fundamental and frequently used commands.

Navigation and Basic System Commands

• Router>: User EXEC mode prompt (limited commands).

• Switch>: User EXEC mode prompt (limited commands).

• Router#: Privileged EXEC mode prompt (all monitoring commands, allows entry to config modes).

• Switch#: Privileged EXEC mode prompt (all monitoring commands, allows entry to config modes).

• Router(config)#: Global Configuration mode prompt.

• Switch(config)#: Global Configuration mode prompt.

• enable: Enter privileged EXEC mode from user EXEC mode.

• disable: Exit privileged EXEC mode to user EXEC mode.

• configure terminal (or config t): Enter global configuration mode.

• exit: Exit the current configuration mode or log out from user EXEC mode.

• end: Exit all configuration modes and return to privileged EXEC mode.

• logout: Log out from the current session.

• ?: Displays context-sensitive help for commands.

• <command> ?: Displays arguments for a command.

• <command> <partial-argument>?: Displays options for a partial argument.

• <command> (tab): Autocompletes a command.

Basic Device Configuration

• hostname <name>: Sets the hostname of the device (Global config).
• enable secret <password>: Sets an encrypted privileged EXEC mode password (Global config).
• enable password <password>: Sets a clear-text privileged EXEC mode password (less secure, Global config).
• service password-encryption: Encrypts all clear-text passwords in the configuration (Global config).
• banner motd #<text>#: Configures a Message Of The Day banner (Global config). The # can be any character not in the text.
• line console 0: Enters console line configuration mode (Global config).
• password <password>: Sets a password for the line (Line config).
• login: Requires password authentication for the line (Line config).
• exec-timeout <minutes> <seconds>: Sets the inactivity timeout for the line (Line config).
• logging synchronous: Prevents console messages from interrupting command input (Line config).
• line vty 0 4: Enters virtual terminal (Telnet/SSH) line configuration mode (Global config). 0 4 typically means 5 VTY lines.

Interface Configuration

• interface <type> <number> (e.g., interface GigabitEthernet0/1, interface FastEthernet0/0): Enters interface configuration mode (Global config).
• ip address <ip-address> <subnet-mask>: Assigns an IP address and subnet mask to the interface (Interface config).
• no shutdown: Activates the interface (Interface config).
• shutdown: Deactivates the interface (Interface config).
• description <text>: Adds a description to the interface (Interface config).
• ipv6 address <ipv6-address>/<prefix-length>: Assigns an IPv6 address to the interface (Interface config).
• ipv6 address autoconfig: Enables IPv6 stateless autoconfiguration (SLAAC) on the interface (Interface config).
• duplex <auto|full|half>: Sets the duplex mode (Interface config).
• speed <auto|10|100|1000>: Sets the interface speed (Interface config).

VLANs (Switches Only)

• vlan <vlan-id>: Creates a VLAN and enters VLAN configuration mode (Global config).
• name <vlan-name>: Assigns a name to the VLAN (VLAN config).
• interface <type> <number>: Selects an interface (Global config).
• switchport mode access: Configures the interface as an access port (Interface config).
• switchport access vlan <vlan-id>: Assigns the access port to a specific VLAN (Interface config).
• switchport mode trunk: Configures the interface as a trunk port (Interface config).
• switchport trunk encapsulation <dot1q|isl>: Specifies the trunking encapsulation (Interface config).
• switchport trunk allowed vlan <vlan-list>: Allows specific VLANs on the trunk (Interface config).
• switchport trunk native vlan <vlan-id>: Sets the native VLAN for the trunk (Interface config).
• no vlan <vlan-id>: Deletes a VLAN (Global config).

Routing (Routers Primarily)

Static Routing

• ip route <destination-network> <subnet-mask> <next-hop-ip | exit-interface>: Configures a static route (Global config).
• ip route 0.0.0.0 0.0.0.0 <next-hop-ip | exit-interface>: Configures a default route (Global config).
• no ip route <destination-network> <subnet-mask> <next-hop-ip | exit-interface>: Removes a static route (Global config).

OSPF (Open Shortest Path First)

• router ospf <process-id>: Enables OSPF routing process (Global config).
• network <network-address> <wildcard-mask> area <area-id>: Specifies networks to be included in the OSPF process and their area (Router config).
• passive-interface <interface-type> <number>: Prevents OSPF updates from being sent out a specific interface (Router config).

EIGRP (Enhanced Interior Gateway Routing Protocol)

• router eigrp <asn>: Enables EIGRP routing process (Global config). asn is the Autonomous System Number.
• network <network-address>: Specifies networks to be included in the EIGRP process (Router config).
• no auto-summary: Disables automatic summarization of networks (Router config).

Security

Access Control Lists (ACLs)

• access-list <acl-number> <permit|deny> <source-ip> <source-wildcard> (Standard ACL): Creates a standard IP ACL (Global config).
• access-list <acl-number> <permit|deny> <protocol> <source-ip> <source-wildcard> <destination-ip> <destination-wildcard> [eq|gt|lt|neq] <port> (Extended ACL): Creates an extended IP ACL (Global config).
• ip access-group <acl-number> <in|out>: Applies an ACL to an interface (Interface config).
• ip access-list standard <acl-name>: Creates a named standard ACL (Global config).
• ip access-list extended <acl-name>: Creates a named extended ACL (Global config).
• permit|deny <conditions>: Adds permit/deny statements within a named ACL (Named ACL config).

Port Security (Switches Only)

• interface <type> <number>: Selects an interface (Global config).
• switchport mode access: Configures the interface as an access port (Interface config).
• switchport port-security: Enables port security on the interface (Interface config).
• switchport port-security maximum <number>: Sets the maximum number of secure MAC addresses (Interface config).
• switchport port-security mac-address sticky: Enables sticky learning of MAC addresses (Interface config).
• switchport port-security violation <shutdown|restrict|protect>: Sets the violation mode (Interface config).

SSH Configuration

• ip domain-name <domain-name>: Configures the domain name (Global config).
• crypto key generate rsa: Generates RSA keys for SSH (Global config).
• username <username> secret <password>: Creates a local user (Global config).
• line vty 0 4: Enters VTY line configuration mode (Global config).
• transport input ssh: Allows only SSH connections on VTY lines (Line config).
• login local: Requires local authentication (Line config).

Monitoring and Verification (Show Commands)

These commands are typically run from Privileged EXEC mode (#).

• show version: Displays system hardware, software version, and uptime.
• show running-config (or sh run): Displays the current active configuration in RAM.
• show startup-config (or sh start): Displays the configuration saved in NVRAM (loaded at boot).
• show ip interface brief (or sh ip int brie): Displays a summary of interface IP addresses and status (up/down).
• show interfaces <type> <number>: Displays detailed status and statistics for a specific interface.
• show ip route: Displays the IP routing table.
• show cdp neighbors detail: Displays detailed information about directly connected Cisco devices.
• show mac address-table (or show mac address-table dynamic): Displays the MAC address table on a switch.
• show vlan brief: Displays a summary of VLANs and their assigned ports.
• show interfaces trunk: Displays trunk port status and allowed VLANs.
• show ip protocols: Displays information about active routing protocols.
• show controllers <type> <number>: Displays hardware-specific information for an interface.
• show log: Displays system log messages.
• show users: Displays current console and VTY users.
• show history: Displays previously entered commands.
• show flash:: Displays contents of flash memory.

Troubleshooting Commands

• ping <ip-address|hostname>: Tests IP connectivity.
• traceroute <ip-address|hostname>: Traces the path packets take to a destination.
• telnet <ip-address|hostname>: Opens a Telnet connection to another device.
• debug <feature>: Enables debugging output for a specific feature (use with caution, can impact performance).
• no debug all or undebug all (or u all): Disables all debugging.
• clear ip route *: Clears the IP routing table (use with caution).
• clear mac address-table dynamic: Clears dynamically learned MAC addresses.
• clear line <line-number>: Clears a VTY or console line.

Configuration Management

• copy running-config startup-config (or wr mem or copy run start): Saves the running configuration to NVRAM.
• copy running-config tftp:: Copies the running configuration to a TFTP server.
• copy tftp: running-config: Copies a configuration file from a TFTP server to running-config.
• erase startup-config: Erases the startup configuration from NVRAM.
• reload: Reboots the device.
• archive log config: Configures logging of configuration changes.
• show archive log config all: Shows the history of configuration changes.

Git

• Git Commands
  • Git Configuration & Setup
  • Initializing a Repository
  • Basic Git Commands
  • Git Commit (Updated Commands)
  • Branching and Merging
  • Remote Repositories
  • Git Comparison
  • Git Managing History

Git Commands

Documentation can be found here

Git Configuration & Setup

Initializing a Repository

Basic Git Commands

Git Commit (Updated Commands)

Branching and Merging

Remote Repositories

Git Comparison

Git Managing History

GitHub CLI

• Completions
• Examples
  • Create a repository
  • Clone a repository

GitHub CLI, or gh, is a command-line interface to GitHub and GitHub-Gist for use in your terminal or your scripts. Manual is found here and the GitHub page is here.

Install:

winget install --id GitHub.cli

Plugins is found here.

Completions

Add the following to your powershell profile:

Invoke-Expression -Command $(gh completion -s powershell | Out-String)

Examples

Create a repository

• create a repository interactively
  gh repo create

• create a new remote repository and clone it locally
  gh repo create my-project --public --clone

• create a new remote repository in a different organization
  gh repo create my-org/my-project --public

• create a remote repository from the current directory
  gh repo create my-project --private --source=. --remote=upstream

Clone a repository

• Clone a repository from a specific org
  gh repo clone cli/cli

• Clone a repository from your own account
  gh repo clone myrepo

• Clone a repo, overriding git protocol configuration
  gh repo clone https://github.com/cli/cli
gh repo clone git@github.com:cli/cli.git

• Clone a repository to a custom directory
  gh repo clone cli/cli workspace/cli

• Clone a repository with additional git clone flags
  gh repo clone cli/cli -- --depth=1

Misc

• Global .gitignore

Global .gitignore

Set up a global core.excludesfile configuration file and point it to a global .gitignore file located in your home or user directory. Check if you already have this config:

git config --get core.excludesfile

If you have a .gitignore located in your home or user directory:

nix or Windows git bash:

git config --global core.excludesFile '~/.gitignore' 

Windows cmd:

git config --global core.excludesFile "%USERPROFILE%\.gitignore"

Windows PowerShell:

git config --global core.excludesFile "$Env:USERPROFILE\.gitignore" 

For Windows it is set to the location C:\Users\%username%\.gitignore. You can verify that the config value is correct by doing:

git config --global core.excludesFile 

The result should be the expanded path to your user profile's .gitignore. Ensure that the value does not contain the unexpanded %USERPROFILE% string.

Important: The above commands will only set the location of the ignore file that git will use. The file has to still be manually created in that location and populated with the ignore list.

Hyper-V Keyboard Shortcuts

General Shortcuts

By default, the keyboard input and mouse clicks are sent to the virtual machine. So you may need to press CTRL + ALT + LEFT arrow before you use the following shortcut keys.

• Ctrl + N: Create a new virtual machine.
• Ctrl + O: Open an existing virtual machine.
• Ctrl + S: Save the current state of the virtual machine.
• Ctrl + P: Pause the virtual machine.
• Ctrl + R: Reset the virtual machine.
• Ctrl + L: Open the Virtual Machine Connection window for a selected VM.
• Delete: Delete the selected virtual machine.

Virtual Machine Management

• Ctrl + Shift + M: Open the Virtual Machine Settings for the selected VM.
• Ctrl + Shift + I: Open the "Inspect" options for a selected virtual machine.
• Ctrl + Shift + C: Connect to the selected virtual machine.

Snapshot Management

• Ctrl + N: Create a new snapshot of the selected virtual machine.
• Ctrl + Shift + D: Delete the selected snapshot.
• Ctrl + Shift + R: Restore the selected snapshot.

Virtual Switch Management

• Ctrl + Shift + S: Open the Virtual Switch Manager.
• Ctrl + D: Delete the selected virtual switch.

Console Interaction

• Ctrl + Alt + Delete: Send Ctrl + Alt + Delete to the VM.
• Ctrl + Alt + Enter: Toggle full-screen mode for the VM console.

Navigation

• Tab: Move focus to the next item in the interface.
• Shift + Tab: Move focus to the previous item in the interface.
• Arrow Keys: Navigate through the list of virtual machines and settings.

List of Common Ubuntu Commands

• File and Directory Management
• System Information
• Package Management
• User Management
• Networking
• Disk Management
• Search and Find
• Miscellaneous

File and Directory Management

• ls - List directory contents
• ls -a - List all files, including hidden files
• ls -lh - List files with human-readable sizes
• ls -R - List files in directories and subdirectories
• cd [directory] - Change the current directory
• cd .. - Move up one directory
• cd - - Switch to the previous directory
• cd ~ - Change to the home directory
• pwd - Print the current working directory
• mkdir [directory] - Create a new directory
• mkdir -p [path/to/directory] - Create parent directories as needed
• rmdir [directory] - Remove an empty directory
• rm [file] - Remove a file
• rm -r [directory] - Remove a directory and its contents recursively
• rm -f [file] - Force remove a file without confirmation
• cp [source] [destination] - Copy files and directories
• cp -r [source] [destination] - Copy directories recursively
• mv [source] [destination] - Move or rename files and directories
• touch [file] - Create an empty file or update the timestamp of a file
• cat [file] - Concatenate and display file content
• head [file] - Display the first 10 lines of a file
• tail [file] - Display the last 10 lines of a file
• tail -f [file] - Follow the end of a file in real-time
• find [path] -name [filename] - Search for files by name
• find [path] -type f -name '*.txt' - Find all text files
• file [filename] - Determine the file type
• ln -s [target] [link] - Create a symbolic link
• du -sh [directory] - Display disk usage of a directory in human-readable format
• stat [file] - Display file or file system status
• tree - Display a directory structure in a tree format (requires installation)
• xargs - Build and execute command lines from standard input

System Information

• uname -a - Display system information
• top - Display active processes
• htop - Interactive process viewer (requires installation)
• df -h - Show disk space usage
• free -h - Show memory usage
• uptime - Show how long the system has been running
• lscpu - Display CPU architecture information
• lsblk - List block devices
• dmesg - Show kernel ring buffer messages
• ps aux - Display all running processes
• whoami - Show the current user
• last - Show last logged in users
• cat /proc/cpuinfo - Display CPU information
• cat /proc/meminfo - Display memory information
• vmstat - Report information about processes, memory, paging, block I/O, traps, and CPU activity
• lsof - List open files and the processes that opened them
• uptime - Show system load averages and uptime
• hostname - Display the system's hostname

Package Management

• sudo apt update - Update package lists
• sudo apt upgrade - Upgrade installed packages
• sudo apt dist-upgrade - Upgrade packages, handling dependencies
• sudo apt install [package] - Install a package
• sudo apt remove [package] - Remove a package
• apt search [keyword] - Search for a package
• sudo apt autoremove - Remove unnecessary packages
• apt list --installed - List all installed packages
• apt show [package] - Display information about a package
• apt-cache policy [package] - Show package version information
• dpkg -l - List all installed packages using dpkg
• sudo apt purge [package] - Remove a package and its configuration files
• sudo apt-get clean - Clear local repository of retrieved package files
• sudo dpkg -i [package.deb] - Install a .deb package
• sudo apt-mark hold [package] - Prevent a package from being upgraded
• apt-file search [filename] - Search for a file in available packages (requires installation)
• sudo apt edit-sources - Edit the sources list for package management

User Management

• adduser [username] - Add a new user
• deluser [username] - Delete a user
• passwd [username] - Change a user's password
• groups [username] - List groups a user belongs to
• who - Show who is logged in
• last - Show last logged in users
• usermod -aG [group] [username] - Add a user to a group
• sudo su - [username] - Switch to another user
• finger [username] - Show information about a user
• chage -l [username] - Show password aging information
• sudo visudo - Edit the sudoers file
• userdel -r [username] - Delete a user and their home directory
• id [username] - Show user ID and group ID information
• newgrp [group] - Log in to a new group
• groups - List groups for the current user
• sudo usermod -d [new_home] [username] - Change a user’s home directory

Networking

• ifconfig - Display network interfaces (deprecated; use ip addr)
• ip addr - Show IP address and network details
• ping [host] - Check connectivity to a host
• curl [URL] - Transfer data from or to a server
• wget [URL] - Download files from the web
• netstat -tuln - Display listening ports
• traceroute [host] - Trace the route to a network host
• nslookup [domain] - Query DNS for a domain
• dig [domain] - Perform DNS lookup (requires installation)
• whois [domain] - Retrieve domain registration information
• ssh [user]@[host] - Securely connect to a remote server
• scp [file] [user]@[host]:[path] - Securely copy files to a remote server
• ftp [host] - Connect to an FTP server
• telnet [host] [port] - Connect to a host via Telnet (if installed)
• route -n - Display the routing table
• ip link show - Show all network interfaces
• nmap [host] - Network exploration tool and security/port scanner (requires installation)

Disk Management

• mount - List mounted filesystems
• umount [device] - Unmount a filesystem
• fdisk -l - List disk partitions
• df -i - Show inode usage
• du -h [directory] - Show directory size in human-readable format
• lsblk - List block devices with mount points
• badblocks [device] - Check for bad sectors on a disk
• fsck [device] - Check and repair a filesystem
• mkfs.ext4 [device] - Create an ext4 filesystem on a device
• resize2fs [device] - Resize an ext2/ext3/ext4 filesystem
• dd if=[source] of=[destination] - Copy and convert files (use with caution)
• parted [device] - Manage disk partitions interactively
• mount -o loop [file] [mountpoint] - Mount an image file
• pvcreate [device] - Initialize a physical volume for LVM
• vgcreate [volume-group] [device] - Create a volume group in LVM

Search and Find

• find [path] -name [filename] - Search for files by name
• grep [pattern] [file] - Search for a pattern in a file
• locate [filename] - Find files by name quickly
• which [command] - Show the full path of a command
• whereis [command] - Locate the binary, source, and manual page files
• history - Show command history
• echo [text] - Print text to the terminal
• sed 's/[old]/[new]/g' [file] - Replace text in a file
• awk '{print $1}' [file] - Print the first column of a file
• grep -r [pattern] [directory] - Recursively search for a pattern in a directory
• find [path] -type f -exec [command] {} \; - Execute a command on found files
• xargs - Build and execute command lines from standard input
• fuzzyfind [pattern] - Fuzzy search for files (requires installation)

Miscellaneous

• clear - Clear the terminal screen
• man [command] - Display the manual for a command
• alias [name]='[command]' - Create an alias for a command
• unalias [name] - Remove an alias
• exit - Exit the terminal session
• chmod [permissions] [file] - Change file permissions
• chown [user]:[group] [file] - Change file owner and group
• tar -cvf [archive.tar] [directory] - Create a tar archive
• tar -xvf [archive.tar] - Extract a tar archive
• zip [archive.zip] [file] - Create a zip archive
• unzip [archive.zip] - Extract a zip archive
• date - Display the current date and time
• cal - Display a calendar
• export [variable]=[value] - Set an environment variable
• env - Display environment variables
• echo $PATH - Display the current PATH variable
• crontab -e - Edit the cron jobs for the current user

Firewall

• Ubuntu Firewall (UFW) Secure Baseline Configuration
• SSH (adjust port if not using 22)
• HTTP/HTTPS (for web servers)
• DNS
• NTP (Time sync)
• SMTP (Email)
• Rate limiting for SSH (prevent brute force)
• ICMP (ping) - enable carefully
• Block common attack vectors
• Application-Specific
• Finalize
• Check logs
• My ufw

Ubuntu Firewall (UFW) Secure Baseline Configuration

sudo ufw reset  
sudo ufw default deny incoming  
sudo ufw default allow outgoing  

SSH (adjust port if not using 22)

sudo ufw allow 22/tcp comment 'SSH access'

HTTP/HTTPS (for web servers)

sudo ufw allow 80/tcp comment 'HTTP'  
sudo ufw allow 443/tcp comment 'HTTPS'

DNS

sudo ufw allow 53 comment 'DNS'

NTP (Time sync)

sudo ufw allow 123/udp comment 'NTP'

SMTP (Email)

sudo ufw allow 25/tcp comment 'SMTP'  
sudo ufw allow 587/tcp comment 'SMTP Submission'  
sudo ufw allow 465/tcp comment 'SMTPS'  

Rate limiting for SSH (prevent brute force)

sudo ufw limit 22/tcp

ICMP (ping) - enable carefully

sudo ufw allow proto icmp comment 'ICMP (ping)'

Block common attack vectors

sudo ufw deny 23/tcp comment 'Block Telnet'  
sudo ufw deny 135:139/tcp comment 'Block NetBIOS'  
sudo ufw deny 445/tcp comment 'Block SMB'  
sudo ufw deny 1433:1434/tcp comment 'Block MS-SQL'  

Application-Specific

sudo ufw allow 2375/tcp comment 'Docker API'  
sudo ufw allow 2376/tcp comment 'Docker TLS'

sudo ufw allow 6443/tcp comment 'Kubernetes API'
sudo ufw allow 10250/tcp comment 'Kubelet API'

Finalize

sudo ufw enable  
sudo ufw status numbered  
sudo systemctl enable ufw  

Check logs

sudo tail -f /var/log/ufw.log

To delete a rule:

sudo ufw delete [RULE_NUMBER]

My ufw

sudo ufw reset  
sudo ufw default deny incoming  
sudo ufw default allow outgoing
sudo ufw allow 22/tcp comment 'SSH access'
sudo ufw allow 443/tcp comment 'HTTPS'
sudo ufw allow 123/udp comment 'NTP'
sudo ufw allow 25/tcp comment 'SMTP'  
sudo ufw allow 53 comment 'DNS'
sudo ufw allow 587/tcp comment 'SMTP Submission'  
sudo ufw allow 465/tcp comment 'SMTPS'  
sudo ufw limit 22/tcp
sudo ufw deny 23/tcp comment 'Block Telnet'  
sudo ufw deny 135:139/tcp comment 'Block NetBIOS'  
sudo ufw deny 445/tcp comment 'Block SMB'  
sudo ufw deny 1433:1434/tcp comment 'Block MS-SQL'  
sudo ufw enable  
sudo ufw status numbered  
sudo systemctl enable ufw  

Keyboard Shortcuts

• I. General Desktop Environment Shortcuts
  • Window Management
  • Workspace Management (Virtual Desktops)
  • System Actions
  • Universal Text Editing (GUI Applications)
• II. Terminal (Bash/Zsh/Shell) Shortcuts
  • Cursor Movement
  • Text Editing/Deletion
  • History Navigation & Search
  • Terminal Control
• III. System/Boot Level Shortcuts

I. General Desktop Environment Shortcuts

These shortcuts often use the Super key (usually the Windows key on most keyboards) or a combination of Ctrl + Alt.

Window Management

• Alt + Tab: Switch between open applications/windows (hold Alt and repeatedly press Tab to cycle; release Alt to select). Use Alt + Shift + Tab for reverse order.
• Super + Tab: (GNOME) Similar to Alt + Tab, often integrated with Activities overview.
• Super + D or Ctrl + Alt + D: Show/Hide Desktop (minimize/restore all windows).
• Alt + F4: Close the current application window.
• Ctrl + Alt + Esc: Force quit an unresponsive application (changes cursor to a "kill" icon).
• Super + Left Arrow: Snap window to left half of the screen (tiling).
• Super + Right Arrow: Snap window to right half of the screen (tiling).
• Super + Up Arrow: Maximize window.
• Super + Down Arrow: Restore/Minimize window.

Workspace Management (Virtual Desktops)

• Ctrl + Alt + Left Arrow: Switch to the left workspace.
• Ctrl + Alt + Right Arrow: Switch to the right workspace.
• Shift + Ctrl + Alt + Left Arrow: Move the current window to the left workspace.
• Shift + Ctrl + Alt + Right Arrow: Move the current window to the right workspace.
• Super + Page Down: (GNOME) Switch to the next workspace.
• Super + Page Up: (GNOME) Switch to the previous workspace.
• Shift + Super + Page Down: (GNOME) Move current window to the next workspace.
• Shift + Super + Page Up: (GNOME) Move current window to the previous workspace.

System Actions

• Ctrl + Alt + T: Open a new terminal window.
• Alt + F2: Open a "Run Command" dialog (e.g., KRunner in KDE).
• Ctrl + Alt + L or Super + L: Lock the screen.
• Print Screen (PrtSc): Take a screenshot of the entire screen.
• Alt + Print Screen: Take a screenshot of the active window.
• Shift + Print Screen: Take a screenshot of a selected area.
• Ctrl + Alt + Delete: Bring up shutdown/logout options.
• Super key (just press it): Opens the Activities overview, application launcher, or main menu, depending on your DE (e.g., GNOME Activities, KDE Plasma's Application Launcher).

Universal Text Editing (GUI Applications)

• Ctrl + C: Copy selected text.
• Ctrl + X: Cut selected text.
• Ctrl + V: Paste text.
• Ctrl + Z: Undo the last action.
• Ctrl + Y or Ctrl + Shift + Z: Redo the last undone action.
• Ctrl + A: Select all.
• Ctrl + S: Save.
• Ctrl + N: New document/file/window.
• Ctrl + O: Open file.
• Ctrl + P: Print.
• Ctrl + F: Find (in current document/application).
• F1: Open help.

II. Terminal (Bash/Zsh/Shell) Shortcuts

These shortcuts are primarily for navigating and editing text within the command line itself.

Cursor Movement

• Ctrl + A (or Home): Move cursor to the beginning of the line.
• Ctrl + E (or End): Move cursor to the end of the line.
• Ctrl + B (or Left Arrow): Move cursor backward one character.
• Ctrl + F (or Right Arrow): Move cursor forward one character.
• Alt + B (or Ctrl + Left Arrow): Move cursor backward one word.
• Alt + F (or Ctrl + Right Arrow): Move cursor forward one word.
• Ctrl + X (tap twice quickly): Toggle between the start of the line and the current cursor position.

Text Editing/Deletion

• Ctrl + H (or Backspace): Delete character before cursor.
• Ctrl + D (or Delete): Delete character under cursor.
• Alt + Backspace or Ctrl + W: Delete the word before the cursor.
• Alt + D: Delete the word from the cursor to the end of the word.
• Ctrl + U: Delete (cut) everything from the cursor to the beginning of the line.
• Ctrl + K: Delete (cut) everything from the cursor to the end of the line.
• Ctrl + Y: Paste the last deleted/cut text.
• Ctrl + T: Transpose (swap) the last two characters before the cursor.
• Alt + T: Transpose (swap) the last two words before the cursor.
• Alt + U: Uppercase from cursor to end of word.
• Alt + L: Lowercase from cursor to end of word.
• Alt + C: Capitalize the first character of the word.

History Navigation & Search

• Up Arrow / Down Arrow: Scroll through previous/next commands in history.
• Ctrl + R: Reverse incremental search through command history (type to search, Ctrl + R again for next match, Enter to execute, Esc to exit).
• Ctrl + G: Exit history search mode.
• !!: Execute the last command.
• !string: Execute the last command starting with "string".
• !$: Use the last argument of the previous command.

Terminal Control

• Tab: Autocomplete commands, filenames, or directory names (press twice for options if ambiguous).
• Ctrl + C: Interrupt/terminate the currently running foreground process.
• Ctrl + D: Send an End-of-File (EOF) marker (can log you out or exit a program).
• Ctrl + Z: Suspend the current foreground process.
• Ctrl + L: Clear the terminal screen.
• Ctrl + S: Pause terminal output.
• Ctrl + Q: Resume terminal output.
• Ctrl + Shift + C: Copy selected text from the terminal.
• Ctrl + Shift + V: Paste text into the terminal.
• Shift + Insert: Alternative paste (often uses the primary selection buffer).

III. System/Boot Level Shortcuts

These shortcuts are less common for daily use but are useful for troubleshooting or direct system interaction.

• Ctrl + Alt + F1 to F6: Switch to a virtual console (text-based login screen). Use F7 or F8 to return to the graphical desktop.
• Ctrl + Alt + Backspace: Kills the X server, returning to the login screen (often disabled by default).
• Magic SysRq Key: A powerful kernel-level debugging tool for emergencies (requires SysRq key, often shared with Print Screen). Use with extreme caution!
  • Alt + SysRq + R: Raw (take keyboard control).
  • Alt + SysRq + E: Terminate (send SIGTERM to processes).
  • Alt + SysRq + I: Kill (send SIGKILL to processes).
  • Alt + SysRq + S: Sync (sync disk).
  • Alt + SysRq + U: Unmount (remount all filesystems read-only).
  • Alt + SysRq + B: Reboot (immediate reboot).
  • Common mnemonic for a safe reboot: R E I S U B (Raising Elephants Is So Utterly Boring)

Terminal Applications

• Quick Install
  • bat
  • fzf
  • zoxide
  • intelli-shell
  • fd
  • ripgrep
  • eza

Quick Install

sudo apt install bat zoxide fd-find ripgrep

bat

Important: If you install bat this way, please note that the executable may be installed as batcat instead of bat (due to a name clash with another package). You can set up a bat -> batcat symlink or alias to prevent any issues that may come up because of this and to be consistent with other distributions:

mkdir -p ~/.local/bin
ln -s /usr/bin/batcat ~/.local/bin/bat

More info at https://github.com/sharkdp/bat

fzf

To get the most up-to-date version on Ubuntu Server 24.04:

git clone --depth 1 https://github.com/junegunn/fzf.git ~/.fzf
~/.fzf/install

Add the following line to your shell configuration file.

bash:

eval "$(fzf --bash)"

More info at https://github.com/junegunn/fzf

zoxide

Set up the repo:

curl -fsSL https://apt.cli.rs/pubkey.asc | sudo tee -a /usr/share/keyrings/rust-tools.asc
curl -fsSL https://apt.cli.rs/rust-tools.list | sudo tee /etc/apt/sources.list.d/rust-tools.list
sudo apt update

You might need to run sudo apt install zoxide again.

bash:

Add this to the end of your config file (usually ~/.bashrc):

eval "$(zoxide init bash)"

More info at https://github.com/ajeetdsouza/zoxide

intelli-shell

Download repo:

curl -sSf https://raw.githubusercontent.com/lasantosr/intelli-shell/main/install.sh | bash

Enable hotkeys:

mkdir -p ~/.local/share/intelli-shell/bin
curl -sSf https://raw.githubusercontent.com/lasantosr/intelli-shell/main/intelli-shell.sh > ~/.local/share/intelli-shell/bin/intelli-shell.sh

More info at https://github.com/lasantosr/intelli-shell

fd

Note that the binary is called fdfind as the binary name fd is already used by another package. It is recommended that after installation, you add a link to fd by executing command..

ln -s $(which fdfind) ~/.local/bin/fd

.. in order to use fd in the same way as in this documentation. Make sure that $HOME/.local/bin is in your $PATH.

You can use fd to generate input for the command-line fuzzy finder fzf:

export FZF_DEFAULT_COMMAND='fd --type file' export FZF_CTRL_T_COMMAND="$FZF_DEFAULT_COMMAND"

Then, you can type vim <Ctrl-T> on your terminal to open fzf and search through the fd-results.

More info at https://github.com/sharkdp/fd and see the Tips section of the fzf README.

ripgrep

Info at https://github.com/BurntSushi/ripgrep and user guide here: https://github.com/BurntSushi/ripgrep/blob/master/GUIDE.md

eza

Eza is available from deb.gierens.de. The GPG public key is in this repo under deb.asc.

First make sure you have the gpg command, and otherwise install it via:

sudo apt update sudo apt install -y gpg

Then install eza via:

sudo mkdir -p /etc/apt/keyrings wget -qO- https://raw.githubusercontent.com/eza-community/eza/main/deb.asc | sudo gpg --dearmor -o /etc/apt/keyrings/gierens.gpg echo "deb [signed-by=/etc/apt/keyrings/gierens.gpg] http://deb.gierens.de stable main" | sudo tee /etc/apt/sources.list.d/gierens.list sudo chmod 644 /etc/apt/keyrings/gierens.gpg /etc/apt/sources.list.d/gierens.list sudo apt update sudo apt install -y eza

Add an alias and config to bash:

alias e='eza -lha --icons --git --time-style=long-iso --header --group-directories-first'

Note: In strict apt environments, you may need to add the target: echo "deb [arch=amd64 signed-by=...

More info at https://github.com/eza-community/eza

Basic Syntax

• Heading
• Heading with custom id
• My Great Heading
• Bold
• Italic
• Bold and nested italic
• All bold and italic
• Strikethrough
• Emoji
• Highlight
• Subscript
• Superscript
• Blockquote
• Ordered List
• Unordered List
• Nested lists
• Code
• Fenced Code Block
• Horizontal Rule
• Link
• Image
  • Linked image
• Table
• Footnote
• Task List
• Escaping characters

Heading

# H1

H1

## H2  

H2

### H3

H3

Heading with custom id

## My Great Heading {#custom-id}

My Great Heading

Bold

**bold text**

bold text

Italic

*italicized text* 

italicized text

Bold and nested italic

**This text is *extremely* important**

This text is extremely important

All bold and italic

***All this text is important***

All this text is important

Strikethrough

~~The world is flat.~~

The world is flat.

Emoji

That is so funny! :joy: 

That is so funny! 😂

Might need som additional software to work. mdbook-emojicodes works for mdBook.

Here's a list of emojis.

Highlight

I need to highlight these ==very important words==.

I need to highlight these <mark>very important words</mark>

I need to highlight these very important words

Subscript

H~2~O

H<sub>2</sub>O

H₂O

Superscript

X^2^

X<sup>2</sup>

X²

Blockquote

> blockquote

blockquote

> blockquote
>
> > nested blockquote
>

blockquote

nested blockquote

Ordered List

1. First item
1. Second item
1. Third item

1. First item
2. Second item
3. Third item

Unordered List

- First item
- Second item
- Third item

• First item
• Second item
• Third item

Nested lists

1. First list item
   - First nested list item
     - Second nested list item

1. First list item
   • First nested list item
     • Second nested list item

Code

`code` 

code

Fenced Code Block

Three backticks makes a fence. Using a tab or 4 blank spaces instead of backticks also works.

```
{
  "firstName": "John",
  "lastName": "Smith",
  "age": 25
}
```

{
  "firstName": "John",
  "lastName": "Smith",
  "age": 25
}

Language specification is optional.

```ruby
require 'redcarpet'
 = Redcarpet.new("Hello World!")
puts .to_
```  

require 'redcarpet'
 = Redcarpet.new("Hello World!")
puts .to_

Horizontal Rule

---

Link

[Guide](https://www.guide.org)

Guide

[an example](http://example.com/ "Title")

an example

Try [Ubuntu][] for your server.

[Ubuntu]: https://ubuntu.com/download/server "Ubuntu Server LTS"

Try Ubuntu for your server.

Image

![alt text](https://png.pngtree.com/png-vector/20220629/ourmid/pngtree-cartoon-little-penguin-operating-a-plane-png-image_5567890.png "My image")

![Logga][1]

[1]: https://commonmark.org/help/images/favicon.png "Creative Commons licensed"

Linked image

[![Markdown image](https://commonmark.org/help/images/favicon.png)](https://commonmark.org)  

Table

| Item              | In Stock | Price |
| :---------------- | :------: | ----: |
| Python Hat        |   True | 3.99 |
| SQL Hat           |   Truer   | 23.99 |
| Codecademy Tee    |  False   | 19.99 |
| Codecademy Hoodie |  Falser   | 42.9999 |  

Footnote

Here's a sentence with a footnote. [^1]

[^1]: This is the footnote.

Here's a sentence with a footnote. ¹

Task List

- [x] Write the press release
- [ ] Update the website
- [ ] Contact the media

• Write the press release
• Update the website
• Contact the media

Escaping characters

You can use a backslash \ to escape the following characters:

Escape backticks with two backticks.

``Use `code` in your Markdown file.``  

Use four backticks to enclose code blocks.

````
```ruby
require 'rubygems'
require 'asciidoctor'
```
````

1. This is the footnote. ↩

Inline HTML

• Underline
• Color
• Commentary
• Collapsed section
• Align
• Center align
• Keyboard
• Embed video
  • Local source
  • Interwebz source

Underline

<u> Text </u> 

Text

Color

<span style="color: #FF69B4;">Why did the tomato turn red?</span>
<span style="color: #00FFFF;">Because it saw the salad dressing!</span>
<span style="color:red;">your text here in red</span>,
<span style="color:#520099;">or make it blue</span>

Why did the tomato turn red? Because it saw the salad dressing! your text here in red, or make it blue

Commentary

<!-- ingen kommentar -->  

Collapsed section

<details>

<summary>Tips for collapsed sections</summary>

You can add text within a collapsed section. 

You can add an image or a code block, too.

```ruby
   puts "Hello World"
```

</details>

   puts "Hello World"

Align

   Centrera

   Centrera

     Centrera

     Centrera

         Centrera

         Centrera

Center align

<p style="text-align: center;">Text i mitten 

Text i mitten

Keyboard

<kbd>Ctrl</kbd> + <kbd>F</kbd>

Ctrl + F

Embed video

Local source

<video src="imgburn.mp4" width="100%" height="100%" controls></video>

Interwebz source

<iframe width="100%" height="100%"
src="https://www.youtube.com/embed/tgbNymZ7vqY">
</iframe>  

mdBook Options

• Change browser tab title
• Include other files
• Rust Playground
• MathJax support
• Embedify
• Alerts
• Mermaid
• Tabs
  • Global tabs
• Admonish

For more details see mdBook docs

Change browser tab title

{{#title New & improved}}

Include other files

Include line 2-10 of the file rust.rs.

{{#include rust.rs:2:10}}

fn do_things<T>(a: T, b: T)
where
    T: IntoIterator,
    T::Item: Display,
{
    for (e, f) in a.into_iter().zip(b.into_iter()) {
        println!("{} {}", e, f);
    }

Rust Playground

Use Rust Playground to run code in the browser.

Produce editable code that runs in the browser.

```rust,editable
fn main() {
    let number = 5;
    print!("{}", number);
}
```

fn main() {
    let number = 5;
    print!("{}", number);
}
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Non-editable code. Runs in the browser.

```rust
fn main() {
    let x = "Rust";
    print!("{}", x);
}
```

fn main() {
    let x = "Rust";
    print!("{}", x);
}

MathJax support

\\[ \mu = \frac{1}{N} \sum_{i=0} x_i \\]

μ=1N∑i=0xi

Embedify

Get mdBook-embedify. Embed videos, gists & codepens. Option to include banners, scroll-to-top and footer options.

Alerts

Modified and translated version of mdBook-alerts. English and Swedish. See options: https://github.com/thorbjornium/rs-mdbook-alerts

Example:

 > [!NOTERA]  
 > Random text

mdBook's builtin version in html:

<div class="warning">

This is a bad thing that you should pay attention to.

Warning blocks should be used sparingly in documentation, to avoid "warning
fatigue," where people are trained to ignore them because they usually don't
matter for what they're doing.
</div> 

Mermaid

Mermaid Theme

mdBook-mermaid

```mermaid
%%{
  init: {
    'theme': 'base',
    'themeVariables': {
      'primaryColor': '#abcadf',
      'primaryTextColor': '#000',
      'primaryBorderColor': '#abcadf',
      'lineColor': '#fae2b3',
      'secondaryColor': '#89a389',
      'tertiaryColor': '#fff'
    }
  }
}%%
        graph TD
          A[Christmas] -->|Get money| B(Go shopping)
          B --> C{Let me think}
          B --> G[/Another/]
          C ==>|One| D[Laptop]
          C -->|Two| E[iPhone]
          C -->|Three| F[fa:fa-car Car]

style D fill:#cdcdf3,color:#23272e,stroke-opacity:0.2

style E fill:#c8f1f3,color:#23272e,stroke-opacity:0.2

style G fill:#f9e5bc,color:#8c8c8c,stroke-opacity:0.2

style C fill:#839bac,color:#23272e,stroke-opacity:0.2

style B fill:#c7e9d3,color:#23272e,stroke-opacity:0.2

style F fill:#cbd5df,color:#23272e,stroke-opacity:0.2

style Test fill:#dfdfdf,color:#23272e,stroke-opacity:0.2



          subgraph section
            C
            D
            E
            F
            G
          end
          
          
```

Tabs

Get mdbook-tabs

{{#tabs }}
{{#tab name="Tab 1" }}
**Tab content 1**
{{#endtab }}
{{#tab name="Tab 2" }}
_Tab content 2_
{{#endtab }}
{{#tab name="Tab 3" }}
~~Tab content 3~~
{{#endtab }}
{{#endtabs }}

Global tabs

{{#tabs global="test" }}
{{#tab name="Rust" }}

```rust,noplayground  
fn main() {
println!("Hello World!");  
} 
```

{{#endtab }}
{{#tab name="HTML" }}

```html
<p style="text-align:center;">Essential Shortcuts</p>
```

{{#endtab }}
{{#tab name="CSS" }}

```css
.mdbook-tab {
    background-color: var(--table-alternate-bg);
    padding: 0.5rem 1rem;
    cursor: pointer;
    border: none;
    font-size: 1.6rem;
    line-height: 1.45em;
}
```

{{#endtab }}
{{#endtabs }}

fn main() {
println!("Hello World!");  
} 

<p style="text-align:center;">Essential Shortcuts</p>

.mdbook-tab {
    background-color: var(--table-alternate-bg);
    padding: 0.5rem 1rem;
    cursor: pointer;
    border: none;
    font-size: 1.6rem;
    line-height: 1.45em;
}

fn main() {
println!("Hello World!");  
} 

<p style="text-align:center;">Essential Shortcuts</p>

.mdbook-tab {
    background-color: var(--table-alternate-bg);
    padding: 0.5rem 1rem;
    cursor: pointer;
    border: none;
    font-size: 1.6rem;
    line-height: 1.45em;
}

Admonish

Install admonish

Examples:

```admonish
Some text
```

```admonish example
example
```

```admonish quote collapsible=true, title='A title that really <span style="color: #e70073">pops</span>'
To really <b><span style="color: #e70073">grab</span></b> your reader's attention.
```

IPv6

• Unicast
  • 1. Global Unicast Address
  • 2. Unique Local Address (ULA)
  • 3. Link-Local Address
  • 4. Loopback Address
  • 5. Unspecified Address
  • 6. IPv4-Embedded IPv6 Addresses
    • Example Table
• Multicast
  • General Structure
    • Multicast Address Format
  • Flags Field
  • Scope Field
  • Special Multicast Address Types
  • Examples
  • Summary
• Anycast
  • What is an Anycast Address?
  • Key Characteristics
  • IPv6 Anycast Address Examples
  • How Anycast Works
  • Summary Table
• ND, NS, and ULA: The Essentials
  • Summary Table
• Global Unicast Address, GUA
  • Structure of an IPv6 GUA
  • Breakdown of Address Parts
    • 1. Global Routing Prefix (48 bits)
    • 2. Subnet ID (16 bits)
    • 3. Interface ID (64 bits)
  • Allocation Example
  • Key Features
  • Summary Table
• EUI: Calculating IPv6 Interface ID Using EUI-64 from MAC Address 1C-6F-65-C2-BD-F8
  • Step-by-Step EUI-64 Calculation
  • Result
• IPv4 Header Fields vs IPv6 Header Fields
  • Comparison Table: IPv4 vs IPv6 Header Fields
  • Key Differences
  • Visual Summary

Unicast

• One-to-one communication: Data is sent from a single source to a single, specific destination address.
• Typical use: Most internet traffic (web browsing, file downloads) is unicast.
• IPv6 example: Sending a packet from your computer to a specific server.

1. Global Unicast Address

• Publicly routable on the Internet
• Prefix: 2000::/3
• Used for global communication

2. Unique Local Address (ULA)

• Private, not routable on the Internet
• Prefix: FD00::/8
• Used for local communications within a site

3. Link-Local Address

• Valid only within a single local network segment
• Prefix: FE80::/10
• Automatically assigned to every IPv6 interface

4. Loopback Address

• Used by a device to send packets to itself
• Address: ::1/128

5. Unspecified Address

• Indicates the absence of an address
• Address: ::/128

6. IPv4-Embedded IPv6 Addresses

• Allow IPv4 and IPv6 interoperability
• Embed a 32-bit IPv4 address within an IPv6 address, often for transition mechanisms like NAT64, IPv4-mapped, and compatible addresses.
• Common formats:
  • IPv4-mapped IPv6: ::ffff:192.0.2.33 (80 bits zero, 16 bits ones, 32 bits IPv4)
    Used for representing IPv4 addresses in IPv6-only environments, especially in software and NAT64 scenarios
  • IPv4-compatible IPv6: ::192.0.2.33 [deprecated; 96 bits zero, 32 bits IPv4]
  • NAT64/XLAT464: Uses a configurable prefix (e.g., 64:ff9b::/96), followed by the IPv4 address
  • Custom Embedded: Networks can embed IPv4 addresses using various prefix lengths, placing the IPv4 address at specific bits within the IPv6 address

Example Table

Note: Embedding IPv4 in IPv6 addresses is essential for transition and interoperability between IPv4 and IPv6 networks

Multicast

• One-to-many communication: Data is sent from one source to multiple destinations, but only to devices that have joined a specific multicast group.
• Efficient for group communication: Saves bandwidth because the data is only sent once and delivered to all interested receivers.
• Typical use: Streaming media, online conferencing, or network discovery protocols.
• IPv6 example: Sending a video stream to all devices in a multicast group (e.g., all routers on a network).

General Structure

All IPv6 multicast addresses start with the prefix FF00::/8 (the first 8 bits are 11111111 in binary, or FF in hexadecimal).

Multicast Address Format

Example: FF02::1 (All nodes on the local link)

Flags Field

The 4-bit flags field provides additional information about the multicast address:

Scope Field

The 4-bit scope field defines where the multicast is valid:

Special Multicast Address Types

• Solicited-Node Multicast Address: Used by Neighbor Discovery Protocol (NDP). Format: FF02::1:FFXX:XXXX where the last 24 bits come from the unicast/anycast address.
• Well-Known Multicast Groups: Assigned by IANA for specific protocols (e.g., FF02::1 for all nodes, FF02::2 for all routers).

Examples

Summary

• All IPv6 multicast addresses begin with FF.
• The next 4 bits are flags, followed by 4 bits for scope.
• The remaining 112 bits specify the multicast group.
• Scope and flags determine the reach and type of multicast group.
• No broadcast in IPv6; multicast fulfills this role.

Anycast

• One-to-nearest communication: Data is sent from one source to the nearest (in routing terms) member of a group of receivers sharing the same address.
• Used for redundancy and load balancing: Improves availability and performance by routing requests to the closest server.
• Typical use: DNS root servers, content delivery networks (CDNs), and global services like Google DNS.
• IPv6 example: Multiple servers around the world share the same anycast address; a user’s request is automatically routed to the closest server.

What is an Anycast Address?

An IPv6 anycast address is an address assigned to multiple interfaces, typically on different nodes. When a packet is sent to an anycast address, it is routed to the "nearest" interface (according to the routing protocol's metric, such as hop count or cost) that has been assigned that address.

Key Characteristics

• Indistinguishable from Unicast: Anycast addresses are allocated from the unicast address space and look identical to unicast addresses. There is no special prefix or format to distinguish them; their "anycast" property comes from being assigned to multiple interfaces.
• Routing Behavior: Routers deliver packets sent to an anycast address to the closest (in terms of routing distance) node with that address.
• Use Cases: Anycast is commonly used for:
  • Redundancy and load balancing (e.g., DNS root servers, CDN edge nodes)
  • Service discovery and high availability
  • Routing to the nearest gateway or service provider

IPv6 Anycast Address Examples

• Subnet Router Anycast: The lowest address in any IPv6 subnet (where the interface identifier is all zeros) is reserved as the subnet-router anycast address.

For example, in the subnet:

2001:db8:abcd:0012::/64

the anycast address is:

2001:db8:abcd:12::

• Reserved Ranges: The highest 128 interface identifiers in a subnet are also reserved for anycast purposes.

How Anycast Works

1. Assignment: The same unicast address is configured on multiple devices/interfaces.
2. Routing: Each device advertises its route to the shared address. Routers learn multiple paths to the same address.
3. Packet Delivery: When a host sends a packet to the anycast address, the network delivers it to the nearest device (according to the routing protocol).

Summary Table

Note: Anycast addresses provide a way to distribute services across multiple locations, improving redundancy, availability, and response times for clients.

Note: IPv6 does not use broadcast; multicast replaces broadcast functionality.

ND, NS, and ULA: The Essentials

IPv6 ND (Neighbor Discovery), NS (Neighbor Solicitation), and ULA (Unique Local Address) are foundational concepts in IPv6 networking. Here’s a concise breakdown:

IPv6 Neighbor Discovery (ND):

• ND is a protocol in IPv6 that allows devices (nodes) on the same network link to discover each other, learn about routers, resolve Layer 3 (IP) to Layer 2 (MAC) addresses, and maintain reachability information.
• It replaces IPv4’s ARP and ICMP Router Discovery, providing more secure and efficient communication.
• ND uses several ICMPv6 message types, including Neighbor Solicitation (NS) and Neighbor Advertisement (NA), to perform its functions.

Key ND Functions:

• Address resolution (finding a device’s MAC address from its IPv6 address)
• Neighbor reachability detection
• Router and prefix discovery
• Address autoconfiguration (stateless)
• Redirecting hosts to better routes

Neighbor Solicitation (NS):

• NS is a specific message type within ND, used to discover the link-layer (MAC) address of a neighbor or to verify its reachability.
• It is functionally similar to an ARP Request in IPv4 but uses multicast instead of broadcast, making it more efficient.
• NS messages are sent to a solicited-node multicast address derived from the target IPv6 address, ensuring only the relevant device responds.

How it works:

• A host sends an NS message to resolve a neighbor’s MAC address.
• The target device replies with a Neighbor Advertisement (NA), providing its MAC address.
• NS is also used for Duplicate Address Detection (DAD), ensuring no two devices use the same IPv6 address on the network.

Unique Local Address (ULA):

• ULAs are IPv6 addresses meant for local communications within a site or organization, similar to private IPv4 addresses (like 192.168.x.x).
• They are not routable on the global Internet but can be routed within private networks.
• ULA addresses start with the prefix FD00::/8. The rest of the address is generated randomly to ensure uniqueness within the local scope.

Key ULA Points:

• Used for internal-only communication
• Not registered or routed on the Internet
• Replace the deprecated “site-local” IPv6 addresses

Summary Table

These mechanisms are essential for IPv6 networks to operate efficiently, securely, and with minimal manual configuration.

Global Unicast Address, GUA

An IPv6 Global Unicast Address (GUA) is a globally unique, Internet-routable address, equivalent to a public IPv4 address. GUAs are used for devices that need to communicate across the Internet and are assigned by Internet authorities to ensure uniqueness.

Structure of an IPv6 GUA

A typical IPv6 GUA consists of three main parts:

• Prefix: All GUAs start with binary 001 (hex 2 or 3), corresponding to 2000::/3.

Example Address:

2001:0db8:1234:5678:9abc:def0:1234:5678

Breakdown of Address Parts

1. Global Routing Prefix (48 bits)

• Assigned hierarchically (IANA → RIR → ISP → organization)
• Ensures global uniqueness
• Used by routers to forward packets across the Internet

2. Subnet ID (16 bits)

• Allows organizations to divide their address space into multiple subnets
• Functions similarly to subnetting in IPv4, but with more flexibility and scale
• Expressed in hexadecimal notation

3. Interface ID (64 bits)

• Uniquely identifies each interface within a subnet
• Often auto-generated from the device’s MAC address using EUI-64, but can be set manually
• Ensures each device on a subnet has a unique address

Allocation Example

• IANA assigns a large block (e.g., 2001::/16) to a Regional Internet Registry (RIR)
• RIR assigns a smaller block (e.g., 2001:0db8::/32) to an ISP
• ISP assigns a /48 prefix (e.g., 2001:0db8:abcd::/48) to an organization
• Organization subdivides the /48 into multiple /64 subnets using the Subnet ID
• Devices on each subnet get a unique Interface ID

Key Features

• Globally unique and routable: Ensures no address conflicts on the Internet
• Hierarchical allocation: Simplifies routing and address management
• Supports subnetting: Organizations can create many subnets internally
• Large address space: 64-bit Interface ID allows for vast numbers of devices per subnet

Summary Table

In summary:
IPv6 GUAs are globally unique, Internet-routable addresses with a hierarchical structure, enabling scalable, efficient, and conflict-free global networking.

EUI: Calculating IPv6 Interface ID Using EUI-64 from MAC Address 1C-6F-65-C2-BD-F8

Step-by-Step EUI-64 Calculation

1. Split the MAC address into two halves:

   • MAC: 1C-6F-65-C2-BD-F8
   • First half: 1C-6F-65
   • Second half: C2-BD-F8

2. Insert FFFE in the middle:

   • Result: 1C-6F-65-FF-FE-C2-BD-F8

3. Convert to IPv6 notation (grouped by two bytes):

   • 1C6F:65FF:FEC2:BDF8

4. Invert the 7th bit (Universal/Local bit) of the first byte:

   • First byte 1C in binary: 00011100
   • 7th bit (counting from left, zero-based): currently 0
   • Invert it to 1: 00011110 (hex: 1E)
   • So, the new first byte is 1E

5. Final EUI-64 Interface ID:

   • Replace the first byte: 1E6F:65FF:FEC2:BDF8

Result

The interface ID, generated using EUI-64 from the MAC address 1C-6F-65-C2-BD-F8, is: 1E6F:65FF:FEC2:BDF8

IPv4 Header Fields vs IPv6 Header Fields

IPv6 simplifies and streamlines the IP header compared to IPv4, removing or replacing several fields to improve processing efficiency and support new features.

Comparison Table: IPv4 vs IPv6 Header Fields

Key Differences

• IPv6 header is fixed at 40 bytes (IPv4 header is variable: 20–60 bytes).
• Fragmentation fields (Identification, Flags, Fragment Offset) are removed from the main header and handled by an optional extension header in IPv6.
• Header checksum is eliminated in IPv6 to reduce processing overhead.
• Options are replaced by more flexible extension headers in IPv6.
• Flow Label is a new field in IPv6 for special packet handling.
• Address fields are expanded from 32 bits (IPv4) to 128 bits (IPv6).

Visual Summary

OSI Layers

Description

• 1. Physical Layer (Layer 1): The Foundation of Transmission
• 2. Data Link Layer (Layer 2): Reliable Node-to-Node Delivery
• 3. Network Layer (Layer 3): Logical Addressing and Routing
• 4. Transport Layer (Layer 4): End-to-End Communication
• 5. Session Layer (Layer 5): Managing Application Sessions
• 6. Presentation Layer (Layer 6): Data Formatting and Security
• 7. Application Layer (Layer 7): User-Facing Network Services
• OSI Model vs TCP/IP Model
  • Layer Structure Comparison
  • Key Differences

1. Physical Layer (Layer 1): The Foundation of Transmission

• Core Function: The Physical Layer is the most fundamental layer, responsible for the actual transmission of raw, unstructured bit streams over a physical medium. It's the tangible connection between devices.
• Detailed Focus:
  • Physical Media: Defines the characteristics of the physical medium used for transmission, including copper cables (twisted-pair, coaxial), fiber optic cables (single-mode, multi-mode), and wireless radio frequencies (e.g., 2.4GHz, 5GHz, 60GHz).
  • Electrical Specifications: Specifies voltage levels, signal timing, and encoding schemes used to represent bits as electrical signals. This includes concepts like baud rate, signal amplitude, and modulation techniques (e.g., amplitude modulation, frequency modulation, phase modulation, quadrature amplitude modulation).
  • Mechanical Specifications: Defines the physical connectors, pin assignments, and cable specifications. This ensures compatibility between devices from different manufacturers. Examples: RJ45 pinouts, fiber optic connector types (LC, SC, ST, MTP/MPO).
  • Procedural Specifications: Defines the procedures for establishing, maintaining, and terminating the physical connection. Includes specifications for signal timing, synchronization, and handshaking.
  • Topology: Concerned with the physical layout of the network, such as point-to-point, bus, star, ring, or mesh topologies. Defines how devices are physically connected and the physical signal flow.
  • Synchronization: Handles bit synchronization, ensuring that the receiver can accurately interpret the transmitted bits. This involves clocking and timing mechanisms, including clock recovery and bit-level alignment.
• Key Aspects:
  • Deals with signal strength, attenuation (signal loss), and noise (interference).
  • Specifies the bit rate (data transmission speed in bits per second).
  • Includes technologies like Ethernet physical layer standards (10BASE-T, 100BASE-TX, 1000BASE-T, 10GBASE-T, 40GBASE-LR4), fiber optic standards (e.g., 1000BASE-LX, 10GBASE-LR, 40GBASE-ER4), and wireless standards (e.g., 802.11a/b/g/n/ac/ax/be).
  • Deals with signal to noise ratio (SNR), and error rates.
• Examples:
  • Cable types: Cat5e, Cat6, Cat6a, Cat7, Cat8, fiber optic cables (single-mode, multi-mode).
  • Connectors: RJ45, LC, SC, ST, MTP/MPO, USB, HDMI.
  • Network devices: Hubs, repeaters, media converters, transceivers (e.g., SFP, QSFP, CFP), optical amplifiers.
  • NICs (Network Interface Cards), fiber optic modems, wireless transceivers, antennas.
  • Power over ethernet (PoE) standards.
• Data Unit: Bits.

2. Data Link Layer (Layer 2): Reliable Node-to-Node Delivery

• Core Function: The Data Link Layer establishes a reliable link between two directly connected nodes, ensuring error-free data transfer within a local network.
• Detailed Focus:
  • Physical Addressing (MAC Addresses): Uses MAC addresses (Media Access Control addresses) to uniquely identify devices on a local network. Includes 48-bit or 64-bit addresses, the organization of the address (OUI, vendor ID), and the use of multicast and broadcast addresses.
  • Framing: Encapsulates data from the Network Layer into frames, adding header and trailer information for addressing, error detection, and control. Specific frame formats for Ethernet (802.3), Wi-Fi (802.11), and other Layer 2 protocols.
  • Error Detection and Correction: Implements error detection mechanisms (e.g., CRC - Cyclic Redundancy Check, checksums) to detect errors during transmission and may also implement error correction techniques (e.g., forward error correction - FEC).
  • Flow Control: Regulates the flow of data to prevent overwhelming the receiver. Includes techniques like stop-and-wait, sliding window, and backpressure, and the use of buffer management.
  • Media Access Control (MAC): Controls how devices access the shared physical medium, especially in shared media networks (e.g., Ethernet, Wi-Fi). Includes protocols like CSMA/CD (Carrier Sense Multiple Access with Collision Detection), CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance), and token passing.
  • Logical Link Control (LLC): Provides flow control and error detection for the Data Link Layer. It defines the protocols used for data exchange over the link, including service access points (SAPs).
  • VLANs (Virtual Local Area Networks): Allow for the logical segmentation of a physical network.
• Key Aspects:
  • Handles collision detection and avoidance in shared media networks.
  • Implements bridging and switching functions, including spanning tree protocol (STP) and link aggregation.
  • Includes protocols like Ethernet (802.3), Wi-Fi (802.11), PPP (Point-to-Point Protocol), HDLC (High-Level Data Link Control), and L2TP (Layer 2 Tunneling Protocol).
  • Handles quality of service (QoS) at layer 2.
• Examples:
  • Ethernet switches, bridges, wireless access points, network adapters.
  • MAC addresses.
  • Protocols: Ethernet (802.3), Wi-Fi (802.11), PPP, HDLC, Frame Relay, ATM (Asynchronous Transfer Mode), MPLS (Multiprotocol Label Switching).
• Data Unit: Frames.

3. Network Layer (Layer 3): Logical Addressing and Routing

• Core Function: The Network Layer is responsible for logical addressing (IP addresses) and routing data packets across networks, enabling communication between devices on different networks.
• Detailed Focus:
  • Logical Addressing (IP Addresses): Uses IP addresses (Internet Protocol addresses) to uniquely identify devices on a network. Includes IPv4 and IPv6 addressing schemes, subnetting, supernetting, and network address translation (NAT).
  • Routing: Determines the best path for data packets to travel from source to destination, even across multiple networks. Includes routing tables, routing algorithms (e.g., Dijkstra's algorithm, Bellman-Ford algorithm), and routing protocols.
  • Packet Forwarding: Forwards data packets based on their destination IP address. Includes techniques like longest prefix matching, packet switching, and label switching.
  • Fragmentation and Reassembly: Handles fragmentation of large packets into smaller packets for transmission over networks with different MTU (Maximum Transmission Unit) sizes and reassembles them at the destination.
  • Routing Protocols: Implements routing protocols (e.g., OSPF, RIP, BGP, EIGRP, IS-IS) to exchange routing information between routers. Includes distance-vector and link-state routing algorithms, and path vector routing.
  • IP Multicast: Allows the sending of a single packet to multiple destinations.
• Key Aspects:
  • Handles network congestion and quality of service (QoS) at the network layer.
  • Includes protocols like IP (IPv4, IPv6), ICMP (Internet Control Message Protocol), ARP (Address Resolution Protocol), and IPsec (Internet Protocol Security).
  • Handles network layer security.
• Examples:
  • Routers, layer 3 switches, firewalls.
  • IP addresses (IPv4 and IPv6).
  • IP protocols: IP, ICMP, ARP, NAT, IPsec.
  • Routing protocols: OSPF, RIP, BGP, EIGRP, IS-IS.
  • VPNs (Virtual Private Networks).
• Data Unit: Packets.

4. Transport Layer (Layer 4): End-to-End Communication

• Core Function: The Transport Layer provides end-to-end communication between applications, ensuring reliable or unreliable data transfer.
• Detailed Focus:
  • Segmentation and Reassembly: Divides data from the Application Layer into segments (TCP) or datagrams (UDP) for transmission and reassembles them at the destination. Includes sequence numbers, acknowledgment mechanisms, and windowing (sliding window protocol).
  • Port Numbers: Uses port numbers to identify applications on a device. Includes well-known (0-1023), registered (1024-49151), and dynamic/private (49152-65535) port numbers, and the concept of sockets (IP address + port number).
  • Reliable Data Transfer (TCP): Provides reliable, connection-oriented data transfer with error detection (checksum), flow control (windowing, congestion control), and retransmission (ARQ - Automatic Repeat Request). Includes three-way handshake (SYN, SYN-ACK, ACK) for connection establishment, four-way termination (FIN, ACK, FIN, ACK) for connection closure, and congestion control algorithms (e.g., TCP Reno, TCP Cubic, TCP BBR).
  • Unreliable Data Transfer (UDP): Provides unreliable, connectionless data transfer with minimal overhead. Used for applications that prioritize speed over reliability, such as streaming media (voice, video), online gaming, DNS queries, and VoIP.
  • Flow Control: Regulates the flow of data to prevent network congestion and buffer overflows. Includes windowing and buffering techniques, as well as congestion avoidance and congestion control mechanisms.
  • Error Recovery: Implements mechanisms to recover from transmission errors, such as retransmission timeouts (RTO), selective acknowledgments (SACK), and fast retransmit/fast recovery.
  • Multiplexing and Demultiplexing: Allows multiple applications to share a single network connection by using port numbers to differentiate between them.
  • Connection-Oriented vs. Connectionless: Explains the difference between connection-oriented (TCP) and connectionless (UDP) communication, and their respective advantages and disadvantages.
• Key Aspects:
  • Provides end-to-end reliability and flow control.
  • Includes protocols like TCP (Transmission Control Protocol) and UDP (User Datagram Protocol), as well as SCTP (Stream Control Transmission Protocol) and DCCP (Datagram Congestion Control Protocol).
  • Handles quality of service (QoS) by prioritizing certain types of traffic.
• Examples:
  • TCP and UDP protocols.
  • Port numbers (e.g., 80 for HTTP, 443 for HTTPS, 53 for DNS).
  • Sockets.
  • Connection establishment and termination procedures.
• Data Unit: Segments (TCP) or Datagrams (UDP).

5. Session Layer (Layer 5): Managing Application Sessions

• Core Function: The Session Layer establishes, manages, and terminates sessions between applications, controlling the dialog between them.
• Detailed Focus:
  • Session Establishment and Termination: Establishes and terminates communication sessions between applications. Includes session negotiation, authentication, and authorization.
  • Dialog Control: Manages the dialog between applications, determining which party can transmit at any given time (full-duplex, half-duplex, simplex).
  • Synchronization: Provides synchronization points (checkpoints) for data streams, allowing for recovery in case of interruptions. Used for applications that require synchronized data exchange, such as database transactions and file transfers.
  • Session Management: Manages the state of the session, including authentication, authorization, accounting, and session recovery.
  • Token Management: Controls which party has the right to transmit data in a half-duplex communication.
  • Activity Management: Defines the data structure and operations for transferring data.
  • Exception Reporting: Handles exceptional conditions that arise during a session, such as session timeouts and errors.
  • Session Recovery: Provides mechanisms for recovering from session interruptions, such as session resumption and checkpointing.
• Key Aspects:
  • Handles session timeouts and recovery, including session resumption after interruptions.
  • Includes protocols like NetBIOS, SAP (Session Announcement Protocol), RPC (Remote Procedure Call), SCP (Session Control Protocol), and TLS/SSL session management.
  • Primarily used in older applications and protocols.
• Examples:
  • NetBIOS session services.
  • Database session management.
  • Authentication protocols that establish sessions (e.g., Kerberos).
  • Session resumption in TLS/SSL.
• Data Unit: Data.

6. Presentation Layer (Layer 6): Data Formatting and Security

• Core Function: The Presentation Layer handles data translation, encryption, and compression, ensuring that data is in a format that the Application Layer can understand.
• Detailed Focus:
  • Data Translation: Translates data between different formats (e.g., ASCII to EBCDIC, Unicode to UTF-8), ensuring compatibility between systems with different data representations. Includes character encoding, data type conversion, and data structure transformations.
  • Encryption and Decryption: Encrypts data for secure transmission (e.g., using SSL/TLS, AES, DES) and decrypts data at the destination, ensuring confidentiality. Includes symmetric and asymmetric encryption algorithms, key management, and digital signatures.
  • Compression and Decompression: Compresses data to reduce its size for efficient transmission (e.g., using ZIP, JPEG compression, MPEG compression) and decompresses it at the destination, improving bandwidth utilization. Includes lossless and lossy compression algorithms.
  • Data Formatting: Handles data formatting and syntax, ensuring that data is presented in a consistent and understandable way. Includes data structure definitions (e.g., XML, JSON), data type conversions, and data presentation standards.
  • Data Representation: Defines the data format that applications will accept.
• Key Aspects:
  • Handles character encoding, data representation, and data conversion.
  • Includes protocols and standards like SSL/TLS (Secure Sockets Layer/Transport Layer Security), ASN.1 (Abstract Syntax Notation One), JPEG, MPEG, XML, JSON, and MIME (Multipurpose Internet Mail Extensions).
  • Provides data security and data compression services.
• Examples:
  • Encryption protocols used in HTTPS and VPNs.
  • Image and video compression algorithms used in multimedia applications.
  • Data formatting used in web services (XML, JSON).
  • Character encoding used in text documents and web pages.
• Data Unit: Data.

7. Application Layer (Layer 7): User-Facing Network Services

• Core Function: The Application Layer is the topmost layer, providing network services directly to end-user applications. It's the layer that users interact with directly.

• Detailed Focus:

  • Application-Specific Protocols: Provides a set of protocols that are specific to the applications that use them. These protocols define how applications interact with the network.
  • User Interface: Acts as an interface between applications and the underlying network, allowing users to access network services.
  • Data Interpretation: Interprets data received from lower layers and presents it to the user in a meaningful way.
  • Network Services: Provides a wide range of network services, including file transfer, email, web browsing, remote access, and network management.
  • Identifying communication partners: Determine the identity and availability of communication partners for an application with data to transmit.
  • Synchronizing communication: Establish if enough resources exist for the intended communication.
  • Supporting syntax agreement: Establish agreement on procedures for error recovery and control of data integrity.
  • Application Logic: This layer can also contain some application-specific logic, such as data validation, business rules, and user authentication.
  • End-User Interaction: Directly supports user interaction and provides the interface for applications to access network services.

• Key Aspects:

  • Is the only layer that directly interacts with end-user applications.
  • Includes protocols like HTTP, HTTPS, FTP, SMTP, DNS, DHCP, Telnet, SSH, POP3, IMAP, SNMP, REST, SOAP, and SIP (Session Initiation Protocol).
  • Provides services that are essential for everyday network use.

• Examples:

  • HTTP (Hypertext Transfer Protocol) and HTTPS (Hypertext Transfer Protocol Secure): Used for web browsing and secure web transactions.
  • FTP (File Transfer Protocol): Used for transferring files between computers.
  • SMTP (Simple Mail Transfer Protocol): Used for sending email.
  • POP3 (Post Office Protocol version 3) and IMAP (Internet Message Access Protocol): Used for receiving email.
  • DNS (Domain Name System): Used for translating domain names into IP addresses.
  • DHCP (Dynamic Host Configuration Protocol): Used for automatically assigning IP addresses to devices.
  • Telnet and SSH (Secure Shell): Used for remote access to computers and network devices.
  • SNMP (Simple Network Management Protocol): Used for network management and monitoring.
  • REST (Representational State Transfer) and SOAP (Simple Object Access Protocol): Used for web services and API communication.
  • SIP (Session Initiation Protocol): Used for VoIP and multimedia communication.

• Data Unit: Data.### 4. Transport Layer (Layer 4): End-to-End Communication

• Core Function: The Transport Layer provides end-to-end communication between applications, ensuring reliable or unreliable data transfer.

• Detailed Focus:

  • Segmentation and Reassembly: Divides data from the Application Layer into segments (TCP) or datagrams (UDP) for transmission and reassembles them at the destination. Includes sequence numbers, acknowledgment mechanisms, and windowing (sliding window protocol).
  • Port Numbers: Uses port numbers to identify applications on a device. Includes well-known (0-1023), registered (1024-49151), and dynamic/private (49152-65535) port numbers, and the concept of sockets (IP address + port number).
  • Reliable Data Transfer (TCP): Provides reliable, connection-oriented data transfer with error detection (checksum), flow control (windowing, congestion control), and retransmission (ARQ - Automatic Repeat Request). Includes three-way handshake (SYN, SYN-ACK, ACK) for connection establishment, four-way termination (FIN, ACK, FIN, ACK) for connection closure, and congestion control algorithms (e.g., TCP Reno, TCP Cubic, TCP BBR).
  • Unreliable Data Transfer (UDP): Provides unreliable, connectionless data transfer with minimal overhead. Used for applications that prioritize speed over reliability, such as streaming media (voice, video), online gaming, DNS queries, and VoIP.
  • Flow Control: Regulates the flow of data to prevent network congestion and buffer overflows. Includes windowing and buffering techniques, as well as congestion avoidance and congestion control mechanisms.
  • Error Recovery: Implements mechanisms to recover from transmission errors, such as retransmission timeouts (RTO), selective acknowledgments (SACK), and fast retransmit/fast recovery.
  • Multiplexing and Demultiplexing: Allows multiple applications to share a single network connection by using port numbers to differentiate between them.
  • Connection-Oriented vs. Connectionless: Explains the difference between connection-oriented (TCP) and connectionless (UDP) communication, and their respective advantages and disadvantages.

• Key Aspects:

  • Provides end-to-end reliability and flow control.
  • Includes protocols like TCP (Transmission Control Protocol) and UDP (User Datagram Protocol), as well as SCTP (Stream Control Transmission Protocol) and DCCP (Datagram Congestion Control Protocol).
  • Handles quality of service (QoS) by prioritizing certain types of traffic.

• Examples:

  • TCP and UDP protocols.
  • Port numbers (e.g., 80 for HTTP, 443 for HTTPS, 53 for DNS).
  • Sockets.
  • Connection establishment and termination procedures.

• Data Unit: Segments (TCP) or Datagrams (UDP).

OSI Model vs TCP/IP Model

Both the OSI and TCP/IP models are layered frameworks for understanding and designing network protocols, but they differ in structure, purpose, and real-world application.

Layer Structure Comparison

Key Differences

• Number of Layers: OSI has 7 layers; TCP/IP has 4 layers (sometimes depicted as 5).
• Layer Functions: TCP/IP merges OSI’s Application, Presentation, and Session layers into a single Application layer. It also combines Data Link and Physical into Network Access.
• Purpose: OSI is a conceptual, protocol-agnostic reference model; TCP/IP is a practical protocol suite used in real-world networking.
• Usage: TCP/IP underpins the modern Internet; OSI is widely used for teaching, troubleshooting, and network planning.
• Protocol Dependency: OSI is protocol-independent; TCP/IP is built around standard protocols (TCP, IP, etc.).

Switch

• Summary Table of Switch Methods
  • Method Details
    • Store-and-Forward
    • Cut-Through
    • - Fragment-Free
    • - Fast-Forward
  • Visual Comparison
• Ethernet Frame Fields
  • Ethernet Frame Structure
  • Field Descriptions
  • Visual Representation

Summary Table of Switch Methods

Method Details

Store-and-Forward

• Switch receives the entire Ethernet frame into memory.
• Performs a CRC (Cyclic Redundancy Check) to detect errors.
• Only forwards error-free frames.
• Introduces the most latency but ensures data integrity.
• Can connect ports of different speeds.

Cut-Through

• Switch reads only enough of the frame to learn the destination MAC (typically first 6–8 bytes).
• Starts forwarding immediately after determining the output port.
• Lowest latency, but may forward frames with errors.
• Cannot detect or filter out corrupted frames.

- Fragment-Free

• Switch waits for the first 64 bytes of the frame before forwarding.
• 64 bytes is the minimum legal Ethernet frame size; anything smaller is a "runt" (likely a collision fragment).
• Filters out runts but does not check for other errors.
• Provides a balance between speed and error avoidance.

- Fast-Forward

• Often a vendor-specific term for cut-through switching.
• Behavior is essentially the same as cut-through: forwards frames as soon as the destination MAC is read.
• Focuses on minimizing latency.

Visual Comparison

In summary:

• Store-and-forward maximizes reliability but adds delay.
• Cut-through (and fast-forward) minimizes delay but may propagate errors.
• Fragment-free offers a compromise, filtering out the most common collision fragments but not all errors.

Ethernet Frame Fields

An Ethernet frame is a structured packet used for data transmission at the data link layer. It encapsulates both addressing and error-checking information, along with the payload. Here are the main fields in a standard Ethernet II frame:

Ethernet Frame Structure

Field Descriptions

• Preamble: 7 bytes of alternating 1s and 0s for synchronization.
• Start Frame Delimiter (SFD): 1 byte (10101011) indicating the start of the actual frame.
• Destination MAC Address: 6 bytes specifying the intended recipient.
• Source MAC Address: 6 bytes specifying the sender.
• EtherType/Length: 2 bytes; EtherType (≥1536) specifies the upper-layer protocol, or Length (≤1500) for payload size.
• VLAN Tag (optional): 4 bytes inserted after the source MAC for VLAN tagging.
• Payload (Data and Pad): Actual data; minimum 46 bytes (padded if needed), maximum 1500 bytes.
• Frame Check Sequence (FCS): 4 bytes CRC for error detection.

Visual Representation

| Preamble | SFD | Dest MAC | Src MAC | EtherType/Length | [VLAN Tag] | Payload (Data+Pad) | FCS | | 7 B | 1 B | 6 B | 6 B | 2 B | 4 B | 46–1500 B | 4 B |

Note:

• VLAN Tag is optional and present only in VLAN-enabled networks.
• The minimum Ethernet frame size is 64 bytes (including all fields).
• The maximum payload is 1500 bytes, and the maximum frame size (without VLAN) is 1518 bytes.

Powershell 7

Basic handling of Powershell

Press F1 after typing a command to get help or type man before the command.

Press F2 to toggle prediction.

Press Tab to move to or list the next suggestion.

Press Shift + Tab to move to the previous suggestion.

Press → to accept the suggestion.

Press Ctrl + Space to list autocomplete suggestions.

Find the Powershell profile echo $profile or just $profile

Open the Powershell profile in notepad notepad $profile

Print the current PSReadLine key handlers Get-PSReadLineKeyHandler

or press Ctrl + Alt + ?

Misc

Find the file location of the Powershell history file. Edit and remove inaccurate predictions.

Get-PSReadLineOption | select-Object -Property HistorySavePath
# or
(Get-PSReadLineOption).HistorySavePath

Basic Commands

Powershell Scripts

• Usage
  • PSFzf
  • Disks
  • Find files and folders
  • Find fz
  • Find fza
  • Google search
  • eza
  • yt-dlp
  • Get-MyIP
  • Open path in Directory Opus
  • Open path in Explorer
  • List items

Usage

Copy and Paste the scripts into your PowerShell profile. To open your PowerShell profile in VS Code type code $Profile. To open in Notepad type notepad $profile

Most scripts require additional software. Install the following software if you do not have it already:

winget install ajeetdsouza.zoxide
winget install junegunn.fzf
winget install sharkdp.fd
winget install sharkdp.bat
winget install BurntSushi.ripgrep.MSVC
winget install eza-community.eza
winget install jftuga.less

Scoop install zoxide fzf fd bat ripgrep eza less

You will need to install the Visual C++ Redistributable package as well.

Add Invoke-Expression (& { (zoxide init powershell | Out-String) }) to your PowerShell profile

Detailed information can be found by clicking zoxide, fzf, fd, bat, ripgrep, eza and less.

PSFzf

PSFzf installs from PSGallery. More details here.

Install-Module -Name PSFzf

Scoop install PSFzf

Paste the following into your PowerShell profile:

Set-PsFzfOption -PSReadlineChordProvider 'Ctrl+t' -PSReadlineChordReverseHistory 'Ctrl+r'  
Set-PSReadLineKeyHandler -Key Tab -ScriptBlock { Invoke-FzfTabCompletion }  

Type cd and press Ctrl + t and search for the directory you want to navigate to. Hit Enter twice to navigate to the directory.

Press Ctrl + r to list previous commands. Search and hit Enter twice to execute the command.

Press ↑ or ↓ to navigate the list.

Tab completion works out of the box.

Disks

Type disks and hit Enter to display disk information in human readable format.

function disks {

    Get-WmiObject -Class Win32_LogicalDisk |
    Select-Object -Property DeviceID, VolumeName,
    @{Label = 'FreeGb'; expression = { ($_.FreeSpace / 1GB).ToString('F2') } },
    @{Label = 'UsedGb'; expression = { (($_.Size - $_.FreeSpace) / 1GB).ToString('F2') } }, # Calculated Used Space
    @{Label = 'TotalGb'; expression = { ($_.Size / 1GB).ToString('F2') } },
    @{label = 'Free %'; expression = { [Math]::Round(($_.freespace / $_.size) * 100, 2) } } |
    Format-Table
}

Find files and folders

A script with options to view, delete or edit files with external tools.

$env:FZF_DEFAULT_OPTS = @"
--layout=reverse
--cycle
--scroll-off=5
--border
--preview-window=right,60%,border-left
--bind ctrl-u:preview-half-page-up
--bind ctrl-d:preview-half-page-down
--bind ctrl-f:preview-page-down
--bind ctrl-b:preview-page-up
--bind ctrl-g:preview-top
--bind ctrl-h:preview-bottom
--bind alt-w:toggle-preview-wrap
--bind ctrl-e:toggle-preview
"@

    function _fzf_open_path {
        param (
            [Parameter(Mandatory = $true)]
            [string]$input_path
        )
        if ($input_path -match "^.*:\d+:.*$") {
            $input_path = ($input_path -split ":")[0]
        }
        if (-not (Test-Path $input_path)) {
            return
        }
        $cmds = @{
            'bat'    = { bat $input_path }
            'cat'    = { Get-Content $input_path }
            'cd'     = {
                if (Test-Path $input_path -PathType Leaf) {
                    $input_path = Split-Path $input_path -Parent
                }
                Set-Location $input_path
            }
            'remove' = { Remove-Item -Recurse -Force $input_path }
            'echo'   = { Write-Output $input_path }
            'VS Code' = { code $input_path }
        }
        $cmd = $cmds.Keys | fzf --prompt 'Select command> '
        & $cmds[$cmd]
    }

    function _fzf_get_path_using_fd {
        $input_path = fd --type file --follow --exclude .git |
        fzf --prompt 'Files> ' `
            --header-first `
            --header 'CTRL-S: Switch between Files/Directories' `
            --bind 'ctrl-s:transform:if not "%FZF_PROMPT%"=="Files> " (echo ^change-prompt^(Files^> ^)^+^reload^(fd --type file^)) else (echo ^change-prompt^(Directory^> ^)^+^reload^(fd --type directory^))' `
            --preview 'if "%FZF_PROMPT%"=="Files> " (bat --color=always {} --style=plain) else (eza -T --colour=always --icons=always {})'
        return $input_path
    }

    function _fzf_get_path_using_rg {
        $INITIAL_QUERY = "${*:-}"
        $RG_PREFIX = "rg --column --line-number --no-heading --color=always --smart-case"
        $input_path = "" |
        fzf --ansi --disabled --query "$INITIAL_QUERY" `
            --bind "start:reload:$RG_PREFIX {q}" `
            --bind "change:reload:sleep 0.1 & $RG_PREFIX {q} || rem" `
            --bind 'ctrl-s:transform:if not "%FZF_PROMPT%" == "1. ripgrep> " (echo ^rebind^(change^)^+^change-prompt^(1. ripgrep^> ^)^+^disable-search^+^transform-query:echo ^{q^} ^> %TEMP%\rg-fzf-f ^& type %TEMP%\rg-fzf-r) else (echo ^unbind^(change^)^+^change-prompt^(2. fzf^> ^)^+^enable-search^+^transform-query:echo ^{q^} ^> %TEMP%\rg-fzf-r ^& type %TEMP%\rg-fzf-f)' `
            --color 'hl:-1:underline,hl+:-1:underline:reverse' `
            --delimiter ':' `
            --prompt '1. ripgrep> ' `
            --preview-label 'Preview' `
            --header 'CTRL-S: Switch between ripgrep/fzf' `
            --header-first `
            --preview 'bat --color=always {1} --highlight-line {2} --style=plain' `
            --preview-window 'up,60%,border-bottom,+{2}+3/3'
        return $input_path
    }

    function fdg {
        _fzf_open_path $(_fzf_get_path_using_fd)
    }

    function rgg {
        _fzf_open_path $(_fzf_get_path_using_rg)
    }


    # SET KEYBOARD SHORTCUTS TO CALL FUNCTION

    Set-PSReadLineKeyHandler -Key "Ctrl+q" -ScriptBlock {
        [Microsoft.PowerShell.PSConsoleReadLine]::RevertLine()
        [Microsoft.PowerShell.PSConsoleReadLine]::Insert("fdg")
        [Microsoft.PowerShell.PSConsoleReadLine]::AcceptLine()
    }

    Set-PSReadLineKeyHandler -Key "Ctrl+f" -ScriptBlock {
        [Microsoft.PowerShell.PSConsoleReadLine]::RevertLine()
        [Microsoft.PowerShell.PSConsoleReadLine]::Insert("rgg")
        [Microsoft.PowerShell.PSConsoleReadLine]::AcceptLine()
    }

There are two ways to get a file path.

Through ripgrep mode.

Through fd mode.

To open in Ripgrep mode, type rgg and hit Enter or press Ctrl + f.

To open in fd mode, type fdg and hit Enter or press Ctrl + q.

Press ↑ or ↓ to navigate the list. Press Shift + ↑ or ↓ to navigate the preview.

ctrl + s - switch between files and directories

ctrl + u - preview-half-page-up

ctrl + d - preview-half-page-down

ctrl + f - preview-page-down

ctrl + b - preview-page-up

ctrl + g - preview-top

ctrl + h - preview-bottom

ctrl + e - toggle-preview

alt + w - toggle-preview-wrap

Open files or folders with bat, cat, cd, echo or VS Code. Delete with 'remove'.

Find fz

File search script utilizing fzf, ripgrep and bat.

 function fz {
    
        $INITIAL_QUERY = "${*:-}"
        $RG_PREFIX = "rg --column --line-number --no-heading --color=always --smart-case"
        "" |
        fzf --ansi --disabled --query "$INITIAL_QUERY" `
        --bind "start:reload:$RG_PREFIX {q}" `
        --bind "change:reload:sleep 0.1 & $RG_PREFIX {q} || rem" `
        --bind 'ctrl-s:transform:if not "%FZF_PROMPT%" == "1. ripgrep> " (echo ^rebind^(change^)^+^change-prompt^(1. ripgrep^> ^)^+^disable-search^+^transform-query:echo ^{q^} ^> %TEMP%\rg-fzf-f ^& type %TEMP%\rg-fzf-r) else (echo ^unbind^(change^)^+^change-prompt^(2. fzf^> ^)^+^enable-search^+^transform-query:echo ^{q^} ^> %TEMP%\rg-fzf-r ^& type %TEMP%\rg-fzf-f)' `
        --color 'hl:-1:underline,hl+:-1:underline:reverse' `
        --delimiter ':' `
        --prompt '1. ripgrep> ' `
        --preview-label 'Preview' `
        --header 'CTRL-S: Switch between ripgrep/fzf' `
        --header-first `
        --preview 'bat --color=always {1} --highlight-line {2} --style=plain' `
        --preview-window 'up,60%,border-bottom,+{2}+3/3'
        }

Type fz and hit Enter.

Press Ctrl + S to switch between ripgrep and fzf.

Press ↑ or ↓ to navigate the list. Press Enter to select.

Press Shift + ↑ or ↓ to navigate the preview.

Find fza

File searcher script utilizing fzf, fd and bat.

function fza { 
    fd --type file --follow --exclude .git |
    fzf --style=full `
        --bind 'focus:transform-header:file --brief {}' `
        --preview 'bat --color=always {} --style=numbers' `
        --preview-window '~3' --reverse `
    
}

Type fza and hit Enter.

Press ↑ or ↓ to navigate the list.

Press Shift + ↑ or ↓ to navigate the preview.

Google search

Search Google from the command line. Type gog and a search term and hit Enter. Opens in your default browser.

Function search-google {
    $query = 'https://www.google.com/search?q='
    $args | ForEach-Object { $query = $query + "$_+" }
    $url = $query.Substring(0, $query.Length - 1)
    Start-Process "$url"
}

Set-Alias gog search-google

eza

List files with details using the e alias. More information in the eza document.

function e {
    eza `
        --long `
        --hyperlink `
        --icons=always `
        --git-repos `
        --git `
        --header `
        --flags `
        --created `
        --time-style long-iso `
        --group-directories-first `
        --context `
        --total-size `
        --all `

}

yt-dlp

Requires yt-dlp. More information here. A short user guide is available here.

winget install yt-dlp

Scoop install yt-dlp

Type ytm and a link and press Enter.

Function ytm {
    yt-dlp `
        --progress `
        --console-title `
        --video-multistreams `
        --audio-multistreams `
        --format-sort "height:1080,fps" `
        --format "bestvideo+bestaudio/best" `
        --check-formats `
        --merge-output-format "mp4/mkv" `
        --recode-video "mp4/mkv" `
        --embed-thumbnail `
        --embed-metadata `
        --embed-chapters `
        --force-keyframes-at-cuts `
        --sponsorblock-mark "all" `
        --write-auto-subs --sub-lang "en.*" `
        $args
}

Get-MyIP

Fetch WAN ip.

function Get-MyIP {
    (Invoke-RestMethod -Uri "https://api.ipify.org")
}

Paste into your $Profile

Open path in Directory Opus

function Open {
    $opusPath = "C:\Program Files\GPSoftware\Directory Opus\dopus.exe"
    $folderPath = Get-Location

    $folderPath = $folderPath -replace '\{', '' -replace '\}', ''

    Start-Process $opusPath -ArgumentList "/path `"$folderPath`""
}

Open path in Explorer

function Open {
    $folderPath = Get-Location
    Invoke-Item $folderPath
}

List items

function ll { Get-ChildItem -Force | Format-Table -AutoSize }
function la { Get-ChildItem -Force -Attributes Hidden, ReadOnly, System | Format-Table -AutoSize }
function l { Get-ChildItem -Name }

Tools

.. that I find useful for Powershell

• IntelliShell
  Bookmarks commands and includes tldr pages.

• zoxide
  Jump straight to directories.

• fzf
  A command-line fuzzy finder.

• ripgrep
  A fast file search tool.

• bat
  Like cat but better.

• yazi
  Tabbed file manager with preview supporting numerous file types.

• fd
  A simple, fast and user-friendly alternative to find.

• eza
  Like ls but better.

• glow
  A terminal-based Markdown viewer.

IntelliShell

• Hotkeys
• Help

IntelliShell bookmarks commands and includes tldr pages.

Press Ctrl + Space to list bookmarked commands.

Type the beginning of the command, for example docker and intelli-shell will fetch a list of commands starting with docker from your bookmarked commands and tldr.
Navigate with ↑ or ↓. Select with Enter.

Hotkeys

ctrl + b bookmark currently typed command

ctrl + space show suggestions for current line

ctrl + l replace labels of currently typed command (Linux)

esc clean current line, this binding can be skipped if INTELLI_SKIP_ESC_BIND=1

Note: When navigating items, selected suggestion can be deleted with ctrl + d or edited with any of: ctrl + e, ctrl + u or F2

You can customize key bindings using environment variables: INTELLI_BOOKMARK_HOTKEY, INTELLI_SEARCH_HOTKEY and INTELLI_LABEL_HOTKEY

Help

Usage: intelli-shell.exe [OPTIONS]

More details on IntelliShell and tldr.

zoxide

Installation

winget install ajeetdsouza.zoxide

Add this to the end of your $profile in PowerShell:

Invoke-Expression (& { (zoxide init powershell | Out-String) })

See the zoxide documentation for more information

Getting started

Configuration

Configuration Flags

When calling zoxide init, the following flags are available:

--cmd
    Changes the prefix of the z and zi commands.
    --cmd j would change the commands to (j, ji).
    --cmd cd would replace the cd command.

--hook <HOOK>

    Changes how often zoxide increments a directory's score:
    Hook    Description
    none    Never
    prompt  At every shell prompt
    pwd (default)   Whenever the directory is changed

--no-cmd
    Prevents zoxide from defining the z and zi commands.
    These functions will still be available in your shell as __zoxide_z 
    and __zoxide_zi, should you choose to redefine them.

Environment variables

Environment variables can be used for configuration. They must be set before zoxide init is called.

_ZO_DATA_DIR

    Specifies the directory in which the database is stored.

    The default value varies across OSes:
    OS               Path               Example
    Linux / BSD    $XDG_DATA_HOME or $HOME/.local/share     /home/alice/.local/share
    macOS   $HOME/Library/Application Support   /Users/Alice/Library/Application Support
    Windows    %LOCALAPPDATA%    C:\Users\Alice\AppData\Local

_ZO_ECHO
    When set to 1, z will print the matched directory before navigating to it.

_ZO_EXCLUDE_DIRS

    Excludes the specified directories from the database.

    This is provided as a list of globs, separated by OS-specific characters:
    OS      Separator     Example
    Linux / macOS / BSD   :    $HOME:$HOME/private/*
    Windows     ;    $HOME;$HOME/private/*

    By default, this is set to "$HOME".

_ZO_FZF_OPTS
    Custom options to pass to fzf during interactive selection.
    See man fzf for the list of options.

_ZO_MAXAGE
    Configures the aging algorithm, which limits the maximum number
    of entries in the database.
    By default, this is set to 10000.

_ZO_RESOLVE_SYMLINKS
    When set to 1, z will resolve symlinks before adding directories to the database.

Set environment variables

Assuming you want to set the _ZO_ECHO variable to 1:

Add this to your $profile in PowerShell:

env:_ZO_ECHO = '1'

Help

Usage: zoxide.exe <COMMAND>

fzf

• Usage
• Help File
  • Search
  • Input/Output
  • Global Style
  • Display Mode
  • Layout
  • List Section
  • Input Section
  • Preview Window
  • Header
  • Scripting
  • Key/Event Binding
  • Advanced
  • Directory Traversal
  • History
  • Shell Integration
  • Help
  • Environment Variables

Install:

winget install junegunn.fzf

Scoop install fzf 

Install Psfzf after fzf. Quick install instructions here.

Usage

Use arrow keys ↑ and ↓ to move cursor up and down. Enter to select the item, Ctrl + C / Ctrl + G / Esc to exit
On multi-select mode (-m), TAB and Shift + TAB to mark multiple items

Mouse: scroll, click, double-click; shift-click and shift-scroll on multi-select mode

Press Ctrl + T to start PSFzf to select provider paths.
Press Ctrl + R to start PSFzf to select a command in the command history saved by PSReadline.
PSFzf will insert the command into the current line, but it will not execute the command.

Press Alt + C to start fzf in folder mode. Press Enter to cd into the selected directory.

A few scripts are here

More details here

Help File

fzf [options]

Search

• -e, --exact - Enable exact-match
• +x, --no-extended - Disable extended-search mode
• -i, --ignore-case - Case-insensitive match
• +i, --no-ignore-case - Case-sensitive match
• --smart-case - Smart-case match (default)
• --scheme=SCHEME - Scoring scheme [default|path|history]
• -n, --nth=N[,..] - Limit search scope using field index expressions
• --with-nth=N[,..] - Transform line presentation using field index expressions
• -d, --delimiter=STR - Field delimiter regex (default: AWK-style)
• +s, --no-sort - Do not sort results
• --literal - Do not normalize Latin script letters
• --tail=NUM - Maximum number of items to keep in memory
• --disabled - Disable search
• --tiebreak=CRI[,..] - Sorting criteria when scores are tied
  • [length|chunk|pathname|begin|end|index] (default: length)

Input/Output

• --read0 - Read input delimited by ASCII NUL characters
• --print0 - Print output delimited by ASCII NUL characters
• --ansi - Enable processing of ANSI color codes
• --sync - Synchronous search for multi-staged filtering

Global Style

• --style=PRESET - Apply a style preset [default|minimal|full[:BORDER_STYLE]
• --color=COLSPEC - Set base color scheme [dark|light|16|bw] and custom colors
• --no-color - Disable colors
• --no-bold - Disable bold text

Display Mode

• --height=[~]HEIGHT[%] - Set window height (fullscreen by default)
• --min-height=HEIGHT[+] - Minimum height when using percentages
• --tmux[=OPTS] - Start fzf in a tmux popup (requires tmux 3.3+)

Layout

• --layout=LAYOUT - Choose layout [default|reverse|reverse-list]
• --margin=MARGIN - Set screen margin
• --padding=PADDING - Set padding inside the border
• --border[=STYLE] - Draw border [rounded|sharp|bold|block|thinblock|double|horizontal|vertical|top|bottom|left|right|none] (default: rounded)
• --border-label=LABEL - Label for the border
• --border-label-pos=COL - Border label position

List Section

• -m, --multi[=MAX] - Enable multi-select
• --highlight-line - Highlight the current line
• --cycle - Enable cyclic scroll
• --wrap - Enable line wrapping
• --gap[=N] - Render empty lines between items
• --scroll-off=LINES - Number of lines to keep above/below during scroll

Input Section

• --no-input - Hide the input section
• --prompt=STR - Set input prompt (default: `> `)
• --info=STYLE - Set finder info style [default|right|hidden|inline[-right][:PREFIX]]

Preview Window

• --preview=COMMAND - Command to preview highlighted line {}
• --preview-window=OPT - Preview window layout (default: right:50%)

Header

• --header=STR - Print a header string
• --header-lines=N - Treat the first N lines as a header
• --header-border[=STYLE] - Border around the header section

Scripting

• -q, --query=STR - Start with the given query
• -1, --select-1 - Auto-select the only match
• -0, --exit-0 - Exit immediately if no match

Key/Event Binding

• --bind=BINDINGS - Define custom key/event bindings

Advanced

• --with-shell=STR - Specify shell command for child processes
• --listen[=[ADDR:]PORT] - Start HTTP server for actions

Directory Traversal

• --walker=OPTS - Set traversal options [file][,dir][,follow][,hidden]
• --walker-root=DIR [...] - Set root directories (default: .)

History

• --history=FILE - Specify history file
• --history-size=N - Max number of history entries (default: 1000)

Shell Integration

• --bash - Setup script for Bash integration
• --zsh - Setup script for Zsh integration
• --fish - Setup script for Fish integration