Linux Networking Cheat Sheet

ip link show

# List network links and their state.

ip addr show

# Display IPv4 and IPv6 addresses on all interfaces.

ip addr show dev eth0

# Inspect addresses for a specific device.

sudo ip link set dev eth0 up

# Enable a network interface.

sudo ip link set dev eth0 down

# Disable a network interface.

sudo ip addr add 192.168.1.10/24 dev eth0

# Assign an additional IP address to an interface.

sudo ip addr del 192.168.1.10/24 dev eth0

# Remove an IP address from an interface.

sudo ip link set dev eth0 mtu 9000

# Change interface MTU size.

sudo ethtool eth0

# Display link speed, duplex, and driver information.

sudo ethtool -S eth0

# Display per-interface statistics exposed by the driver.

nmcli device status

# List devices managed by NetworkManager and their states.

hostname -I

# Print IP addresses assigned to the local host.

ss -ltnp

# List listening TCP sockets with names.

ss -lunp

# List listening UDP sockets with names.

ss -tp state established

# Display established TCP sessions.

ss -ltnp '( sport = :443 )'

# Find sockets using a specific local port.

sudo lsof -iTCP:8080 -sTCP:LISTEN -n -P

# Find which process owns a TCP port.

sudo lsof -i -n -P

# List network connections for all processes.

sudo fuser 5432/tcp

# Identify processes using a TCP port.

nc -vz example.com 443

# Check whether a remote TCP port is reachable.

nc -lv 9000

# Open a simple TCP listener for testing.

socat TCP-LISTEN:8080,fork TCP:127.0.0.1:80

# Create a TCP port forward with socat.

watch -n 2 'ss -s; echo; ss -ltnp'

# Refresh socket view every 2 seconds.

sudo tcpdump -i eth0

# Capture packets on a specific network interface.

sudo tcpdump -i any tcp port 443

# Capture traffic for a single TCP port.

sudo tcpdump -i any host 10.0.0.5

# Capture traffic to or from a host.

sudo tcpdump -i any -w capture.pcap

# Save a capture to a file for Wireshark analysis.

tcpdump -nn -r capture.pcap

# Inspect a saved packet capture file.

mtr example.com

# Continuously test latency and path quality.

iperf3 -s

# Start a throughput test server.

iperf3 -c 10.0.0.10

# Benchmark throughput to a remote host.

iperf3 -c 10.0.0.10 -R

# Measure reverse-direction throughput.

sudo ping -f 10.0.0.10

# Send packets as fast as possible for stress testing.