When configuring a server or troubleshooting connectivity issues, understanding Linux networking commands is essential. The older net-tools suite (like ifconfig) is largely deprecated in favor of the newer iproute2 suite.

The Versatile ip Command

The ip command is the modern standard for viewing and configuring network interfaces, routing, and tunnels.

• View IP Addresses:

  ip addr show

  This lists all network interfaces and their assigned IP addresses. (You can also use the shorthand ip a).
• View Routing Table:

  ip route show

  This shows how the system decides where to send network traffic.

Checking Connectivity: ping

The ping command is the simplest way to check if a remote host is reachable. It sends ICMP Echo Request packets and waits for a reply.

ping google.com

Note: On Linux, ping runs indefinitely by default. Press Ctrl+C to stop it, or use the -c flag to specify a count (e.g., ping -c 4 google.com).

DNS Lookups: dig and host

When you need to resolve domain names to IP addresses or investigate DNS records, use dig or host.

host example.com
dig example.com

dig provides much more detailed output, making it better for advanced DNS troubleshooting.

Checking Open Ports and Connections

To see what services are listening on your machine and what connections are currently active, use ss (socket statistics), which replaces the older netstat.

ss -tuln

• -t: Show TCP sockets.
• -u: Show UDP sockets.
• -l: Show only listening sockets.
• -n: Show numerical addresses (don’t resolve IPs to hostnames).

Mastering these commands allows you to diagnose network issues quickly and efficiently from the terminal.