ifconfig

Why ip is Better than ifconfig

ifconfig is a legacy tool with a simpler, less structured approach. ip offers an improved interface, providing more detailed control over network interfaces and routing tables. Its structured approach makes complex configurations much easier to manage and understand.

Basic Network Interface Management with ip

Let’s start with the fundamentals. The core functionality of ifconfig is encompassed by the ip addr command.

Displaying Interface Information:

The simplest use of ip addr is to list all network interfaces and their associated addresses:

ip addr show

This will output information including the interface name (e.g., eth0, wlan0, lo), its IP address, subnet mask, and other details.

Setting a Static IP Address:

To configure a static IP address on an interface, use the following syntax:

ip addr add 192.168.1.100/24 dev eth0

This sets the IP address 192.168.1.100 with a netmask of /24 on the eth0 interface. Remember to replace eth0 with the actual name of your interface and adjust the IP address and netmask accordingly.

Setting a Static IP Address with Gateway and DNS:

For a more complete configuration including a default gateway and DNS servers, you’ll need to use additional ip commands:

ip addr add 192.168.1.100/24 dev eth0
ip route add default via 192.168.1.1
ip route add 8.8.8.8 dev eth0 #for google dns
ip route add 8.8.4.4 dev eth0 #for google dns

This adds a default route via the gateway 192.168.1.1 and adds google’s DNS servers to the routing table.

Deleting an IP Address:

To remove an IP address from an interface:

ip addr del 192.168.1.100/24 dev eth0

Bringing Interfaces Up and Down:

To bring an interface up (activate it):

ip link set eth0 up

To bring an interface down (deactivate it):

ip link set eth0 down

Working with Network Namespaces

ip also provides powerful tools for managing network namespaces, allowing for isolation of network configurations. This is beyond the scope of a basic introduction, but it highlights the extended capabilities ip provides compared to ifconfig.

Advanced Usage (Brief Overview)

The ip command offers much more than what’s covered here. Explore the ip route, ip link, and ip netns commands for advanced routing, interface management, and network namespace manipulation respectively. Consult the man ip page for exhaustive documentation. Understanding these capabilities provides much more detailed control over your network configurations.