Freeing Up a Stuck Port in Linux Using SS and Kill

Step 1: Find the Process Using the Port

Use the ss (socket statistics) command to list all processes listening on a specific port:

ss -tulnp | grep 8080

• -t: TCP

• -u: UDP

• -l: Listening sockets

• -n: Show numerical addresses

• -p: Show process using the socket

You’ll get output similar to:

tcp LISTEN 0 511 *:8080 *:* users:(("MainThread",pid=237743,fd=21))

Step 2: Extract the PID

To isolate the PID from that line:

ss -tulnp | grep 8080 | awk '{print $NF}' | cut -d ',' -f 2 | cut -d '=' -f 2

This command chain:

• Extracts the last field using awk

• Splits by comma and selects the PID field

• Splits by = to get the actual PID

Example output:

237743

Step 3: Kill the Process

Once you have the PID, terminate it:

kill -9 237743

Or automate the whole process in one line:

kill -9 $(ss -tulnp | grep 8080 | awk '{print $NF}' | cut -d ',' -f 2 | cut -d '=' -f 2)

This forcefully kills the process holding onto port 8080.

Summary

When a port is stuck:

1. Use ss -tulnp to identify the process.

2. Extract the PID.

3. Kill the process using kill -9