How can I tell what port my postgreSQL server is running on?

I didn't specify one, and it was installed as part of RedHat 7.3, so I'm guessing its 5432.

My real problem is that MS SQL 7.0 says,
Could not connect to server.
Could not connect to remote socket.

I searched the archives, and they said to
1) make sure postgreSQL is running by doing a psql <database name>
2) Make sure you specify the correct port for your server

the psql thing works fine, and I'm pretty sure the services are up, network is connected, machines can ping each other.

Thanks

Keith