- All
TCP sockets. - All UDP sockets.
- All established ssh / ftp / http / https connections.
- All local processes connected to X server.
- All the
tcp sockets in state FIN-WAIT-1 and much more.
Most Linux distributions are shipped with ss and many monitoring tools. Being familiar with this tool helps enhance your understand of what's going on in the system sockets and helps you find the possible causes of a performance problem.
Task: Display Sockets Summary
# ss -s
Sample Output:
Total: 734 (kernel 904)TCP : 1415 (estab 112, closed 1259, orphaned 11, synrecv 0, timewait 1258/0), ports 566
Transport Total IP IPv6
* 904 - -
RAW 0 0 0
UDP 15 12 3TCP 156 134 22
INET 171 146 25
FRAG 0 0 0
Task: Display All Open Network Ports
# ss -l
Sample Output:
ss -l
Recv-Q Send-Q Local Address:Port Peer Address:Port
0 0 127.0.0.1:smux *:*
0 0 127.0.0.1:10024 *:*
0 0 127.0.0.1:10025 *:*
0 0 *:3306 *:*
0 0 *:http *:*
0 0 *:4949 *:*
0 0 *:domain *:*
0 0 *:ssh *:*
0 0 *:smtp *:*
0 0 127.0.0.1:rndc *:*
0 0 127.0.0.1:6010 *:*
0 0 *:https *:*
0 0 :::34571 :::*
0 0 :::34572 :::*
0 0 :::34573 :::*
0 0 ::1:rndc :::*
# ss -pl
Find out who is responsible for opening socket / port # 4949:
# ss -lp | grep 4949
Sample output:
0 0 *:4949 *:* users:(("munin-node",3772,5))
# cd /proc/3772
# ls -l
Task: Display All TCP Sockets
# ss -t -a
Task: Display All UDP Sockets
# ss -u -a
Task: Display All Established SMTP Connections
# ss -o state established '( dport = :smtp or sport = :smtp )'
Task: Display All Established HTTP Connections
# ss -o state established '( dport = :http or sport = :http )'
Task: Find All Local Processes Connected To X Server
# ss -x src /tmp/.X11-unix/*
Task: List All The Tcp Sockets in State FIN-WAIT-1
# ss -o state fin-wait-1 '( sport = :http or sport = :https )' dst 202.54.1/24