Open Ports: Find Which Program Uses Them in Linux
Oct 06, 2026
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by John Britto
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1 min read
Quick Linux Tip #91 :
Question: I see unexpected open ports. What program is behind each one?
Try: sudo ss -tulnp
Info: ss flags: -t=TCP, -u=UDP, -l=listening, -n=numeric, -p=processes. Displays active listening sockets alongside process names, PIDs, and file descriptors.
Examples:
$ sudo ss -tulnp | grep :80 # Filter for specific port bindings
$ sudo ss -tnp state established # Identify active inbound and outbound connections
$ sudo lsof -iTCP -sTCP:LISTEN -P -n # Alternative open port diagnostic using lsof
Note: Replaces legacy netstat -tulnp. Bindings on 127.0.0.1 restrict access to localhost, while 0.0.0.0 exposes services publicly.
LinuxTeck.com
linuxteck:~$ sudo ss -tulnp
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port Process
udp UNCONN 0 0 127.0.0.53%lo:53 0.0.0.0:* users:(("systemd-resolve",pid=890,fd=14))
udp UNCONN 0 0 10.0.0.5:68 0.0.0.0:* users:(("NetworkManager",pid=1023,fd=27))
tcp LISTEN 0 128 0.0.0.0:22 0.0.0.0:* users:(("sshd",pid=1245,fd=3))
tcp LISTEN 0 511 0.0.0.0:80 0.0.0.0:* users:(("nginx",pid=2341,fd=6))
tcp LISTEN 0 511 0.0.0.0:443 0.0.0.0:* users:(("nginx",pid=2341,fd=7))
tcp LISTEN 0 128 127.0.0.1:3306 0.0.0.0:* users:(("mysqld",pid=3456,fd=22))
tcp LISTEN 0 128 127.0.0.1:6379 0.0.0.0:* users:(("redis-server",pid=4567,fd=6))
linuxteck:~$
About John Britto
John Britto Founder & Chief-Editor @LinuxTeck. A Computer Geek and Linux Intellectual having more than 20+ years of experience in Linux and Open Source technologies.
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