CentOS Network Configuration

CentOS Network Configuration

Configuring network settings is crucial for ensuring your CentOS system can communicate with other devices on your network and the internet. This guide covers the basics of network configuration on CentOS, including static IP address assignment, DNS configuration, and troubleshooting.

Understanding Network Interfaces

Before configuring your network, identify the network interfaces available on your system with:

nmcli device status

This command lists network devices and their status, helping you determine which interface(s) to configure.

Setting a Static IP Address

CentOS uses NetworkManager and the nmcli tool for network configuration. To set a static IP address for an interface, follow these steps:

1. Disable DHCP on the Interface:

   nmcli con mod [interface-name] ipv4.method manual
   

2. Assign the Static IP Address:

   nmcli con mod [interface-name] ipv4.addresses [your-static-ip]/24
   

3. Set the Default Gateway:

   nmcli con mod [interface-name] ipv4.gateway [gateway-ip]
   

4. Specify DNS Servers:

   nmcli con mod [interface-name] ipv4.dns "[DNS1],[DNS2]"
   

5. Restart NetworkManager to apply the changes:

   systemctl restart NetworkManager
   

Replace [interface-name], [your-static-ip], [gateway-ip], [DNS1], and [DNS2] with your actual network interface name, desired IP address, gateway, and DNS servers.

Configuring DNS

Edit /etc/resolv.conf to set your DNS servers manually:

nameserver [DNS1]
nameserver [DNS2]

This file may be managed by NetworkManager. If you’re using static IP configuration as described above, setting DNS via nmcli is preferred.

Troubleshooting Network Issues

If you encounter network connectivity issues:

• Ensure your network cable is properly connected and your router or switch is operational.
• Check your network configuration with nmcli con show [interface-name] and verify the settings.
• Test connectivity to your gateway and external addresses using ping.
• Review system logs with journalctl -u NetworkManager for any NetworkManager-related errors.

Advanced Configuration

For more complex network setups, such as bonding, bridging, or VLAN tagging, refer to the official CentOS documentation. These scenarios often require additional configuration steps and understanding of network principles.

By following this guide, you should now have a basic understanding of how to configure network settings on your CentOS system. Remember, network configuration can vary widely based on your specific environment and requirements, so always tailor these instructions to fit your situation.