What Is Using Port 8080 on Ubuntu? Check With ss

If an Ubuntu application reports “Address already in use” on TCP port 8080, first identify the listener. These commands inspect sockets and do not stop processes.

Check the listening socket

ss -ltn 'sport = :8080'

A LISTEN row with 127.0.0.1:8080 means the socket is bound to IPv4 loopback. A wildcard address such as 0.0.0.0:8080 means it listens on all local IPv4 interfaces. That does not tell you whether a firewall permits remote access. No row means no matching TCP listener was visible in the current network namespace at that moment.

Identify the owner

ss -ltnp 'sport = :8080'

The process column may show a program name and PID. If the owner is hidden, an authorized administrator can repeat the same inspection with sudo. For containers, inspect the relevant namespace as well as any host-published ports.

Decide what should own the port

For example, if a local development server already owns the port, choose a different configured port for your second server or stop the first one using its normal controls once you confirm it is yours. If a managed service fails, see the Ubuntu service log guide. Avoid killing an unfamiliar PID.

Ubuntu ss manual.