If the admin doesn't set the ssh service port on default 22, how can I find the port that he set?

Question

If the admin doesn't set the ssh service port on default 22, how can I find the port that he set? Trust me I don't plan to doing bad things. I am just curious!

update: The ssh service port is on 521. I can be sure. Because i can use ssh login via 521.
nmap addresshided -sV
Starting Nmap 5.51 ( http://nmap.org ) at 2011-09-30 09:38 CST
Nmap scan report for addresshided
Host is up (0.0052s latency).
Not shown: 996 filtered ports
PORT    STATE  SERVICE VERSION
23/tcp  closed telnet
80/tcp  closed http
443/tcp closed https
631/tcp closed ipp

Service detection performed. Please report any incorrect results at http://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 5.45 seconds

I think i need to study nmap further. Thank you for all the reply. :-)

Answer 1

nmap [ip] -sV

or, if on the local machine:

netstat -tlp | grep -i ssh

Answer 2

Seriously, send them an email and ask.

Answer 3

You can use this easy to use online tool port scanner. It will list out all the open ports and what are the configured for.
---EDIT--
You could use the following commands :

$ lsof
This lists out all you open ports
$ netstat -nan | grep 22
This will give you detail of theport specified

Answer 4

Run the following in a terminal:

lsof | grep IPv4 | grep ssh

1. lsofwill list all open files and ports.
2. grep IPv4 weeds out everything except open IP sockets
3. grep ssh shows only lines with ssh.

If you look through the results, you should be able to find which ports are in use by the ssh process.