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Network Commands Cheatsheet

A handy reference guide to essential network commands for administration and troubleshooting.

Basic Network Information

IP Configuration

ip addr

Display IP addresses, subnet masks, and interface information.

Example:

ip addr show eth0

ifconfig

Display or configure network interface parameters (deprecated, but still used).

Example:

ifconfig eth0

hostname

Display the system’s hostname.

Example:

hostname

hostname -I

Display all IP addresses associated with the hostname.

Example:

hostname -I

nmcli

NetworkManager command-line tool for managing network connections.

Example:

nmcli device show eth0

ethtool

Display or change Ethernet card settings.

Example:

ethtool eth0

Routing

route

Display or manipulate the IP routing table.

Example:

route -n

ip route

Show or manipulate routing, devices, policy routing and tunnels.

Example:

ip route show

traceroute

Traces the route packets take to a network host.

Example:

traceroute google.com

Network Connectivity

Testing Connectivity

ping

Send ICMP ECHO_REQUEST packets to network hosts.

Example:

ping google.com

telnet

Connect to a remote system using the Telnet protocol (unencrypted).

Example:

telnet example.com 80

nc (netcat)

Arbitrary TCP and UDP connections and listens. Good for testing network services.

Example:

nc -zv example.com 20-30

curl

Transfer data from or to a server.

Example:

curl example.com

wget

Retrieve files from the web.

Example:

wget https://example.com/file.txt

DNS Lookup

nslookup

Query Internet name servers interactively.

Example:

nslookup example.com

dig

DNS lookup utility. More powerful and flexible than nslookup.

Example:

dig example.com

host

DNS lookup utility for finding the IP address associated with a hostname or vice versa.

Example:

host example.com

Network Monitoring

Traffic Monitoring

tcpdump

A powerful packet analyzer; it prints a description of the contents of network packets.

Example:

tcpdump -i eth0

wireshark

A network protocol analyzer that lets you capture and interactively browse the traffic running on a computer network. (GUI based).

Example:
Start Wireshark from the GUI or use tshark (command-line version).

tshark -i eth0

iftop

Displays bandwidth usage on an interface by host.

Example:

iftop -i eth0

nload

Displays network usage in real-time.

Example:

nload eth0

Connection Monitoring

netstat

Displays network connections, routing tables, interface statistics, masquerade connections, and multicast memberships.

Example:

netstat -an

ss

ss is used to dump socket statistics. It allows showing information similar to netstat.

Example:

ss -tulpn

lsof

List open files. Can be used to find processes using network connections.

Example:

lsof -i :80

Firewall Management

iptables

iptables -L

List current iptables rules.

Example:

iptables -L

iptables -A INPUT -p tcp --dport 22 -j ACCEPT

Add a rule to accept SSH traffic.

Example:

iptables -A INPUT -p tcp --dport 22 -j ACCEPT

iptables -D INPUT -p tcp --dport 22 -j ACCEPT

Delete a rule.

Example:

iptables -D INPUT -p tcp --dport 22 -j ACCEPT

firewalld

firewall-cmd --state

Check the status of firewalld.

Example:

firewall-cmd --state

firewall-cmd --zone=public --add-port=80/tcp --permanent

Open port 80 for HTTP traffic permanently.

Example:

firewall-cmd --zone=public --add-port=80/tcp --permanent

firewall-cmd --reload

Reload firewalld to apply changes.

Example:

firewall-cmd --reload
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