How to Quickly Identify Which Process Is Using a Specific Port on Linux

Netstat and ss commands

Both netstat and ss can display listening sockets and the processes that own them. Install the required tools if they are missing (e.g., yum install -y net-tools for netstat, yum install -y iproute for ss).

Example using netstat to find processes listening on port 8888: netstat -anlp | grep 8888 Key options: -t: show TCP ports -u: show UDP ports -l: show only listening sockets -p: display PID and program name -n: show numeric addresses (skip DNS lookup)

Typical columns in the output:

Proto : protocol (tcp or udp)

Recv-Q : bytes waiting to be read by the local process

Send-Q : bytes waiting to be transmitted

Local Address : IP and port on the local host (e.g., 0.0.0.0:22 for all IPv4 interfaces, :::22 for all IPv6 interfaces, 127.0.0.1:9100 for loopback only)

Foreign Address : remote endpoint (same format as local address)

State : connection state such as LISTEN, ESTABLISHED, or UNKNOWN PID/Program : process ID and the executable using the socket

To achieve the same with ss:

ss -anlp | grep 80

lsof command

The lsof utility lists open files and the processes that opened them; network sockets are treated as files. Install it if necessary ( yum install -y lsof).

lsof -i:80

fuser command

fuser

shows which processes are using a specific file or socket. Install it via yum install -y psmisc. Example to check which process owns TCP port 22:

fuser 22/tcp -v

nmap tool

nmap

can scan local ports quickly. No extra installation steps are shown, but the basic usage is: nmap localhost Reference link: https://www.cnblogs.com/myitnews/p/11516730.html