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ifconfig Command on ChromeOS Linux Environment

The ifconfig command is a network configuration utility used to view and manage network interfaces. While ifconfig is considered deprecated in favor of ip in many modern Linux distributions, it is still included in several systems and remains a useful tool for network management. On ChromeOS Linux (Crostini), ifconfig can help users diagnose and configure network interfaces.

Syntax

The basic syntax of the ifconfig command is:

bash ifconfig [interface] [options]

Key Components:

  • interface: Specifies the network interface (e.g., eth0, wlan0).
  • options: Modifies the behavior or displays specific information.

Examples of Usage

View All Network Interfaces

To display information about all network interfaces:

bash ifconfig

Example Output: bash eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.1.100 netmask 255.255.255.0 broadcast 192.168.1.255 inet6 fe80::1e6f:65ff:fe7a:1c21 prefixlen 64 scopeid 0x20<link> ether 00:1e:65:7a:1c:21 txqueuelen 1000 (Ethernet) RX packets 12345 bytes 987654 (987.6 KB) TX packets 6789 bytes 432109 (432.1 KB)

Display Information for a Specific Interface

To view details about a specific interface, such as eth0:

bash ifconfig eth0

Enable a Network Interface

To activate a network interface:

bash sudo ifconfig eth0 up

Disable a Network Interface

To deactivate a network interface:

bash sudo ifconfig eth0 down

Assign an IP Address

To manually assign an IP address to a network interface:

bash sudo ifconfig eth0 192.168.1.150 netmask 255.255.255.0

Change the MTU Size

To modify the Maximum Transmission Unit (MTU) size of a network interface:

bash sudo ifconfig eth0 mtu 1400

Add an Alias to an Interface

To create an alias for a network interface:

bash sudo ifconfig eth0:1 192.168.1.200 netmask 255.255.255.0

Troubleshooting

Check for ifconfig Availability

If ifconfig is not installed, you can add it by installing the net-tools package:

bash sudo apt update sudo apt install net-tools

Permission Denied

Administrative privileges are required for certain operations. Use sudo when needed:

bash sudo ifconfig eth0 up

Interface Not Found

Ensure the specified interface exists by listing all interfaces:

bash ifconfig -a

Deprecation Notice

Although ifconfig is still available on many systems, it has been replaced by the ip command for modern network configuration tasks. For example:

  • To display interfaces: bash ip addr

  • To activate an interface: bash sudo ip link set eth0 up

  • To assign an IP address: bash sudo ip addr add 192.168.1.150/24 dev eth0

Best Practices

  1. Prefer ip for New Scripts: Use the ip command for modern network management tasks.
  2. Verify Interface Names: Check interface names with ifconfig -a or ip addr before making changes.
  3. Use with Caution: Changes made with ifconfig are temporary and reset after a reboot unless configured in network scripts.

The ifconfig command is a legacy tool but remains useful for quick diagnostics and configuration in the ChromeOS Linux environment. For long-term or complex tasks, consider transitioning to the ip command.