How to Check Network Connections on Linux

Understanding network connections helps troubleshoot connectivity and security issues.

Show Active Connections

ss -tuln

Flags: -t TCP, -u UDP, -l listening, -n numeric.

Show All Connections with Process Info

ss -tulnp

Show Established Connections

ss -tn state established

Network Interfaces

ip addr show
ip link show

Routing Table

ip route show

Test Connectivity

# Ping
ping -c 4 google.com

# DNS lookup
dig google.com
nslookup google.com

# Traceroute
traceroute google.com