whatis port
Port
Also known as: TCP port, UDP port, listening port
A number from 0 to 65535 that identifies a specific service on a host, like 22 for SSH, 80 for HTTP, and 443 for HTTPS.
What Is a Network Port in Linux?
An IP address gets traffic to the right machine; the port gets it to the right program. Services "listen" on a port, and clients connect to it. Ports below 1024 are privileged and require root or a capability to bind.
ss -tulnp lists listening TCP and UDP ports with the owning process. Closing unused ports and firewalling the rest is one of the simplest server hardening steps.
Example
sudo ss -tulnpLearn more about Port
- Checking Open Ports on Linux Knowing which ports are open and which processes are listening on them is essential for security audits, debugging, and firewall configuration. This guide covers ss, lsof, nmap, and related tools.
- netcat Explained: Testing Ports, Moving Files, and Debugging Protocols netcat reads and writes arbitrary TCP and UDP connections, which makes it the fastest way to answer is this port actually open and what is that service really saying.
- Linux Firewall Basics Linux firewalls control which network traffic is allowed in and out of your system. This guide covers the concepts, ufw for simple setups, and an introduction to the underlying nftables rules that power them all.