Essential Linux Network Commands Every Sysadmin Should Know

Linux Network Commands Overview

This guide collects common Linux networking tools, offering brief introductions, simple demo commands, and useful tips to help you remember and use them efficiently during troubleshooting.

ping

Tests connectivity and measures latency; can also resolve domain names. ping www.baidu.com By default it sends packets continuously; use -c to limit count, -W for timeout, -I to select an interface, and -b for broadcast. Press Ctrl+\ during execution to display a summary.

netstat

Shows current network connections, listening ports, and routing tables. netstat -lnpt To view the routing table:

netstat -nr

lsof

Lists open files; with -i it can filter network sockets. lsof -i :22 Shows which process (e.g., sshd) is listening on port 22.

Iftop

Displays real‑time bandwidth usage per host on an interface.

tcpdump

Command‑line packet capture tool capable of capturing any protocol, similar to Wireshark.

Example: capture traffic to 192.168.73.128 on port 22.

telnet

Telnet client can also be used to test port reachability.

Connecting to localhost port 22 confirms the port is open and shows the banner.

ifconfig

Traditional network interface configuration tool; shows IP address, packet statistics, and can enable/disable interfaces.

whois

Queries domain registration information such as owner, email, and registrar.

route

Displays and modifies the routing table.

ip

Powerful replacement for many older tools (ifconfig, netstat, route, arp).

brctl

Manages Linux bridges; can create, delete, and add interfaces to bridges.

traceroute

Shows each hop between the local host and a destination, useful for locating network bottlenecks.

mtr

Combines ping and traceroute, continuously updating hop statistics.

ss

Fast socket statistics tool, more efficient than netstat for large numbers of connections.

Common options: -l (listening), -t (TCP), -4 (IPv4), -n (no DNS).

axel

Multi‑threaded download accelerator that splits a file into multiple connections for faster retrieval.

Example: axel -n 20 http://example.com/file.iso It supports resume and is noticeably faster than wget.

Summary

Key Linux networking tools include configuration utilities (ifconfig, ip), routing tools (route, netstat, ip), port inspection (netstat, lsof, ss, telnet), download accelerators (curl, wget, axel), firewalls (iptables, ipset), traffic monitors (iftop, nethogs), connectivity checks (ping, traceroute, mtr, tracepath), domain utilities (nslookup, dig, whois), web servers (python, nginx), packet capture (tcpdump), and bridge management (brctl, ovs).