Essential Linux Networking Commands Cheat Sheet

1. ping

Purpose: Test network connectivity to another host.
Usage: ping [destination]
Example: ping google.com
Description: Sends ICMP Echo Request packets to the target and reports if replies are received, helping verify if a host is reachable.

2. traceroute

Purpose: Trace the path packets take to a network destination.
Usage: traceroute [destination]
Example: traceroute google.com
Description: Displays each hop (router) along the route to the target and the time taken for each hop, useful for diagnosing routing issues.

3. netstat

Purpose: Display network connections, routing tables, interface statistics, and more.
Usage: netstat [options]
Common options:

• -a : Show all connections and listening ports

• -t : Show TCP connections

• -u : Show UDP connections

• -l : Show only listening sockets

Example: netstat -tuln
Description: Lists all listening TCP and UDP ports in numeric form

4. curl

Purpose: Make HTTP requests and interact with URLs or APIs.
Usage: curl [options] [URL]
Example: curl https://example.com
Description: Retrieves content from a web server, useful for testing web services and APIs.

5. dig

Purpose: Query DNS servers for information about hostnames and IP addresses.
Usage: dig [hostname]
Example: dig google.com
Description: Provides detailed DNS query results, including IP addresses, authoritative servers, and more.

6. nslookup

Purpose: Query DNS to obtain domain name or IP address mapping.
Usage: nslookup [hostname]
Example: nslookup google.com
Description: Returns the IP address associated with a domain name, or vice versa.

7. ip

Purpose: Manage and display network interfaces, IP addresses, and routing.
Usage:

• ip link show

• sudo ip link set eth0 down

• ip route show

Description: Shows network interfaces, manages their state, and displays routing tables. Replaces older tools like ifconfig and route.

8. mtr

Purpose: Combine ping and traceroute for real-time network diagnostics.
Usage: mtr [destination]
Example: mtr google.com
Description: Shows the route to a host and updates statistics in real time, useful for detecting packet loss and latency.

9. whois

Purpose: Query domain registration and ownership details.
Usage: whois [domain]
Example: whois example.com
Description: Retrieves domain registration information from public databases.

10. tcpdump

Purpose: Capture and analyze network packets in real time.
Usage: sudo tcpdump -i [interface] [filter]
Example: sudo tcpdump -i eth0 port 80
Description: Captures packets for analysis. Useful for troubleshooting network traffic.

11. ifplugstatus

Purpose: Check the physical link status of network interfaces.
Usage: ifplugstatus [interface]
Example: ifplugstatus eth0
Description: Verifies if an Ethernet cable is connected.

12. nmcli

Purpose: Manage NetworkManager connections and devices from the command line.
Usage:

• nmcli device show

• nmcli connection show
  Description: Displays and manages network devices and connections.

13. nc (netcat)

Purpose: Versatile networking utility for port scanning, data transfer, and connectivity checks.
Usage: nc -v -n [destination] [port]
Example: nc -v -n 192.168.1.10 22
Description: Checks if a port is open, can transfer files, and more.

14. telnet

Purpose: Test TCP connectivity to a specific port.
Usage: telnet [destination] [port]
Example: telnet 192.168.1.10 22
Description: Connects to a remote host on a given port, useful for troubleshooting services.

15. arp

Purpose: Display and modify the ARP table.
Usage: arp -a
Description: Shows the mapping of IP addresses to MAC addresses on the local network.

16. route

Purpose: Display or modify the IP routing table.
Usage: route -n
Description: Shows the system’s routing table (mostly replaced by ip route).