How to Use the ip Command in Linux to Manage Network Interfaces and Routing

For decades, system administrators and Linux users relied on legacy net-tools utilities—primarily ifconfig, route, and arp—to inspect and configure network adapters. However, net-tools was officially deprecated in the Linux kernel ecosystem years ago due to its inability to handle complex modern networking features such as multi-table policy routing, VLAN tagging, network namespaces, and modern IPv6 address structures. In modern Linux distributions (including Ubuntu, Debian, Red Hat, Fedora, and Arch), the definitive, universal command-line utility for managing network interfaces, IP addresses, ARP tables, and routing is the ip command (part of the iproute2 package).

Why iproute2 Replaced the Legacy net-tools Suite

The ip command communicates directly with the Linux kernel via the modern Netlink socket interface:

• Direct Netlink Protocol Communication: Unlike ifconfig, which relies on outdated ioctl system calls, ip talks directly to the kernel’s Netlink subsystem, delivering instantaneous configuration updates and event notifications.
• Unified Command Structure: Replaces dozens of fragmented legacy binaries (ifconfig, route, arp, netstat -r) with a single, consistent hierarchical syntax.
• Advanced Routing & Policy Control: Supports multiple independent routing tables, policy routing rules, and isolated network namespaces for Linux containers (Docker and Podman).
• Modern Abbreviation Syntax: Commands can be abbreviated cleanly (for example, typing ip a instead of ip address show).

Understanding the Hierarchical Syntax of the ip Command

Every ip command follows a predictable structure:

ip [options] OBJECT COMMAND [arguments]

The primary OBJECTS include:

• link (or l): Physical and virtual network interface devices (Ethernet, Wi-Fi, bridges, loopback).
• address (or a, addr): IPv4 and IPv6 protocol addresses assigned to interfaces.
• route (or r): IP routing table entries and default gateway paths.
• neigh (or n): Neighbour cache (ARP and IPv6 ND mappings).

Inspecting and Managing IP Addresses (ip addr)

To inspect active network addresses and adapters across your machine:

1. Displaying All Network Addresses

ip addr show

(Or simply: ip a).

The output displays all interfaces (e.g., eth0, enp3s0, wlan0), their MAC addresses (link/ether), assigned IPv4 addresses (inet), and IPv6 addresses (inet6).

2. Filtering by a Specific Interface

ip addr show dev eth0

3. Assigning a Temporary Static IP Address

To assign an IPv4 address with subnet mask (CIDR notation) to an interface:

sudo ip addr add 192.168.1.150/24 dev eth0

4. Deleting an Assigned IP Address

sudo ip addr del 192.168.1.150/24 dev eth0

Managing Network Interface States (ip link)

To view physical link statuses and toggle devices on or off:

1. Listing All Physical Interfaces

ip link show

2. Bringing an Interface Up or Down

Equivalent to the legacy ifconfig eth0 up and ifconfig eth0 down:

sudo ip link set dev eth0 down
sudo ip link set dev eth0 up

3. Modifying the Interface MTU (Maximum Transmission Unit)

To enable Jumbo Frames for high-speed local storage transfers (e.g., setting MTU to 9000 bytes):

sudo ip link set dev eth0 mtu 9000

Inspecting and Managing the Routing Table (ip route)

Routing rules determine which network gateway your Linux machine contacts to dispatch outbound packets:

1. Displaying the Active Routing Table

ip route show

(Or simply: ip r).

Look for the default via line, which identifies your default internet gateway IP address.

2. Adding a Default Gateway

sudo ip route add default via 192.168.1.1 dev eth0

3. Adding a Static Route to a Specific Subnet

To route all traffic destined for the 10.50.0.0/16 network through a secondary router at 192.168.1.254:

sudo ip route add 10.50.0.0/16 via 192.168.1.254 dev eth0

4. Deleting a Route

sudo ip route del 10.50.0.0/16

Inspecting the ARP / Neighbour Cache (ip neigh)

To view mappings between local IP addresses and physical MAC addresses (replaces the legacy arp -a command):

ip neigh show

To flush or clear the local ARP cache during network changes:

sudo ip neigh flush all

ip Command vs Legacy net-tools (Quick Reference)

Action	Modern ip Command (iproute2)	Legacy net-tools Command
View all IP addresses	ip addr show (or ip a)	ifconfig -a
Add an IP address	ip addr add 192.168.1.50/24 dev eth0	ifconfig eth0 192.168.1.50 netmask 255.255.255.0
Disable an interface	ip link set dev eth0 down	ifconfig eth0 down
View routing table	ip route show (or ip r)	route -n or netstat -r
View ARP table	ip neigh show	arp -a

Making Configuration Changes Permanent

Changes executed directly via the ip command apply instantly to the running Linux kernel, but are ephemeral; they reset upon a system reboot. To make static IP assignments and routing permanent:

• On Ubuntu / Debian: Edit your YAML network configuration in /etc/netplan/ and apply with sudo netplan apply.
• On RHEL / CentOS / Rocky Linux: Use NetworkManager via nmcli or configure connection profiles in /etc/NetworkManager/system-connections/.

Frequently Asked Questions

Can I display coloured and formatted output with the ip command?

Yes. Pass the -c (colour) flag for readable, syntax-highlighted output: ip -c a or ip -c r.

How do I assign multiple IP addresses to a single interface without aliases?

Unlike ifconfig which required virtual alias devices (like eth0:1), the ip command natively supports multiple IPs on one physical device. Simply run sudo ip addr add 192.168.1.101/24 dev eth0 and both addresses will co-exist seamlessly.

Is the ip command available on minimal Linux server images?

Yes. The iproute2 package is an essential core component included on virtually every Linux distribution and container image.