netcat
A small tool that opens or listens on network connections, used to test whether a port answers.
In more detail
nc -z host port tests a TCP port without sending data, and nc -l port listens, which stands in for a service during tests. A refused connection means nothing listens on that address and port.
Related terms
- ss — The Linux command that lists network sockets, such as which ports are listening and which connections are open.
Taught in
- A Server Nobody Can Find: Addresses, Routes And Names On Both Families — CompTIA Linux+ (XK0-006) Exam Prep
- The Tracker Is Down, For Some People: Link, Address, Route, Name And Port — CompTIA Linux+ (XK0-006) Exam Prep
- Network Troubleshooting: The Ladder From Link To Port — Linux Foundation Certified System Administrator (LFCS) Exam Prep
- Network Troubleshooting: A Ladder Of Questions — LPIC-1 Linux Administrator (101-500 and 102-500) Exam Prep