Master the ifconfig Command: Manage Network Interfaces in Linux

What is the ifconfig Command?

Envision the ifconfig command as a network control panel, displaying and configuring network interfaces like eth0 or wlan0. While still useful, it’s largely replaced by the ip command in modern Linux distributions.

Why ifconfig is Essential

Syntax and Options

The ifconfig command manages network interfaces:

ifconfig [interface] [options]
        

Key options:

• up: Activate an interface.
• down: Deactivate an interface.
• netmask: Set subnet mask.
• address: Assign IP address.

Alternative: Use ip addr or ip link for modern systems.

Real-World Examples

1. List All Interfaces

Type this:

ifconfig
        

Output: Lists interfaces like eth0, lo, with IPs and status.

2. Activate an Interface

Enable eth0:

sudo ifconfig eth0 up
        

Output: Activates eth0.

3. Assign an IP Address

Set IP for eth0:

sudo ifconfig eth0 192.168.1.100 netmask 255.255.255.0
        

Output: Assigns IP 192.168.1.100.

4. Deactivate an Interface

Disable eth0:

sudo ifconfig eth0 down
        

Output: Deactivates eth0.

5. View Specific Interface

Check wlan0 details:

ifconfig wlan0
        

Output: Shows wlan0 IP, MAC, and stats.

Advanced Usage

Elevate ifconfig with these techniques:

• MTU Adjustment: Use mtu 1400 to set MTU size.
• Alias Interfaces: Create virtual interfaces (e.g., eth0:1).
• Script Integration: Automate network setup in scripts.
• Modern Alternative: Use ip link set eth0 up instead.

Example: Set MTU:

sudo ifconfig eth0 mtu 1400
        

Pro Tips

Server Setup: Use for temporary IP assignments.

Debugging: Check interface status before troubleshooting.

Switch to ip: Use ip addr show for modern systems.

Common Mistakes to Avoid

Avoid these pitfalls with ifconfig:

• Using on Modern Systems: Prefer ip for compatibility.
• Missing sudo: Configuration requires root privileges.
• Persistent Changes: Changes via ifconfig are temporary.

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