ip — Network Management Command

What is ip?

The ip command is a powerful, versatile tool used to configure and manage network interfaces, routes, IP addresses, and other network-related tasks on Linux systems. It is part of the iproute2 package, which provides modern tools for network management, replacing older tools like ifconfig, route, and netstat.

ip offers a wide range of functionalities for network configuration and troubleshooting, including the management of network interfaces, routing tables, network addresses, tunnels, and more.

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Key Features of ip

• Interface Management: View and modify network interfaces, assign IP addresses, bring interfaces up or down.

• Routing: View and configure network routes and IP forwarding.

• Network Address Management: Assign and remove IP addresses to network interfaces.

• Multicast and Tunnels: Handle multicast addresses and set up network tunnels.

• Advanced Options: Provides detailed control over various networking features, including link-layer configuration and quality of service.

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Basic Syntax

ip [options] OBJECT {COMMAND | help}

Where:

• OBJECT is the network object (e.g., link, addr, route).

• COMMAND is the action you want to perform (e.g., show, add, del).

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Common ip Subcommands

1. ip link — Manage Network Interfaces

Used to manage network interfaces (e.g., Ethernet, Wi-Fi, virtual interfaces).

Example Commands

• Show all network interfaces:

  ip link show

• Bring an interface up:

  sudo ip link set eth0 up

• Bring an interface down:

  sudo ip link set eth0 down

• Change the MAC address of an interface:

  sudo ip link set eth0 address 00:11:22:33:44:55

• Enable promiscuous mode:

  sudo ip link set eth0 promisc on

2. ip addr — Manage IP Addresses

Used to manage IP addresses assigned to network interfaces.

Example Commands

• Show all IP addresses:

  ip addr show

• Add an IP address:

  sudo ip addr add 192.168.1.100/24 dev eth0

• Remove an IP address:

  sudo ip addr del 192.168.1.100/24 dev eth0

• Assign an IP address with a specific scope:

  sudo ip addr add 192.168.1.100/24 dev eth0 scope global

3. ip route — Manage Routing Tables

Used to display and modify routing tables.

Example Commands

• Show the routing table:

  ip route show

• Add a route:

  sudo ip route add 192.168.2.0/24 via 192.168.1.1 dev eth0

• Delete a route:

  sudo ip route del 192.168.2.0/24 via 192.168.1.1 dev eth0

• Add a default route:

  sudo ip route add default via 192.168.1.1

4. ip link set — Change Interface Settings

Used to change the settings of network interfaces (e.g., bring interfaces up/down, assign addresses).

Example Commands

• Set an interface to promiscuous mode:

  sudo ip link set eth0 promisc on

• Set an interface to non-promiscuous mode:

  sudo ip link set eth0 promisc off

• Change interface MTU (Maximum Transmission Unit):

  sudo ip link set eth0 mtu 1500

5. ip tunnel — Create Tunnels

Used to manage IP tunnels (e.g., GRE tunnels, IPsec tunnels).

Example Commands

• Create a GRE tunnel:

  sudo ip tunnel add tun0 mode gre remote 192.168.1.1 local 192.168.1.2
  sudo ip link set tun0 up

• Show tunnel information:

  ip tunnel show

6. ip link set — Set Interface Attributes

You can set various attributes of network interfaces, including the interface’s name, MTU, and MAC address.

Example Commands

• Set a new name for the interface:

  sudo ip link set eth0 name new_eth0

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Example Use Cases

Use Case 1: Configuring a Static IP Address

To set a static IP address on a network interface:

1. Assign the IP address:

   sudo ip addr add 192.168.1.100/24 dev eth0

2. Bring the interface up:

   sudo ip link set eth0 up

3. Add the default route:

   sudo ip route add default via 192.168.1.1

Use Case 2: Setting Up a Virtual Network Interface

For setting up a virtual interface (e.g., eth0:0):

1. Assign the IP address to the virtual interface:

   sudo ip addr add 192.168.2.100/24 dev eth0 label eth0:0

2. Bring the interface up:

   sudo ip link set eth0:0 up

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Comparison with Older Tools

Feature	ip Command	ifconfig/route
Interface Management	Full-featured management	Limited functionality
IP Address Handling	Advanced capabilities	Basic address assignment
Routing	Advanced routing features	Limited routing features
Tunnels	Supports advanced tunnels (GRE, IPsec)	Limited tunnel support
Efficiency	Preferred tool for modern Linux setups	Deprecated and less efficient

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Alternatives to ip

Tool	Description
ifconfig	Older tool for managing network interfaces, largely replaced by ip.
netplan	For managing network configuration in newer Ubuntu versions (YAML-based).
nmcli	NetworkManager's command-line interface for managing network connections.

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Summary

Feature	ip Command
Purpose	Manage network interfaces, addresses, and routes on Linux
Common Use Cases	IP configuration, route management, interface management
Alternatives	ifconfig, nmcli, netplan, brctl
Key Commands	ip link, ip addr, ip route, ip tunnel

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The ip command is a robust and modern tool for network configuration on Linux, offering extensive features for managing interfaces, IP addresses, routing, and more. It is the preferred tool for most modern Linux systems, providing superior functionality compared to older tools like ifconfig and route.