How to Check Open Ports on Ubuntu
Checking open ports on your Ubuntu system is essential for security and troubleshooting. Whether you’re running a server or debugging a connection issue, knowing which ports are open and which service is using them can help.
Here are several easy ways to check open ports in Ubuntu.
1. Using ss (Socket Statistics)
The ss command is a modern alternative to netstat and is pre-installed on most Ubuntu systems:
ss -tuln
-t: Show TCP connections-u: Show UDP connections-l: Display listening sockets-n: Show numerical port numbers instead of resolving service names
To get more detailed info (like the process using the port):
sudo ss -tulnp
2. Using netstat (if installed)
If you’re using an older system or prefer netstat, install it via:
sudo apt install net-tools
Then run:
netstat -tuln
Or for process info:
sudo netstat -tulnp
3. Using lsof (List Open Files)
lsof can show which process is using a port:
sudo lsof -i -P -n
To check a specific port (e.g., 80):
sudo lsof -i :80
4. Using nmap for Port Scanning
Install nmap:
sudo apt install nmap
Scan localhost:
nmap -sT localhost
How to Check Open Ports on Ubuntu (F.A.Q)
How can I check if a specific port is open?
Use ss -tuln | grep :PORT, replacing PORT with the desired number.
What is the easiest way to list all listening ports?
Use ss -tuln or sudo lsof -i -P -n.
How do I find which service is using a port?
Run sudo lsof -i :PORT or sudo ss -tulnp | grep :PORT.
Is it safe to expose open ports?
Only if secured and required. Exposing unused or unsecured ports can be a security risk.