check which program uses the port on linux or macOS
check port 22:
lsof -i :22
sshd 30350 root 3u IPv4 181286 0t0 TCP *:ssh (LISTEN) sshd 30350 root 4u IPv6 181288 0t0 TCP *:ssh (LISTEN)
lsofLsof revision 4.93.2 lists on its standard output file information about files opened by processes for the following UNIX dialects:
Apple Darwin 9 and Mac OS X 10. FreeBSD 8., 9.0 and 1.0 for AMD64-based systems Linux 2.1.72 and above for x86-based systems Solaris 9, 10 and 11
(See the DISTRIBUTION section of this manual page for information on how to obtain the latest lsof revision.)
An open file may be a regular file, a directory, a block special file, a character special file, an executing text reference, a library, a stream or a network file (Internet socket, NFS file or UNIX domain socket.) A specific file or all the files in a file system may be selected by path.
Instead of a formatted display, lsof will produce output that can be parsed by other programs. See the -F, option description, and the OUTPUT FOR OTHER PROGRAMS section for more information.
In addition to producing a single output list,
will run in repeat mode.
In repeat mode it will produce output, delay, then repeat the output
operation until stopped with an interrupt or quit signal.
option description for more information.