I believe that Postgres ships with the tcp port closed. You have to open the port by firing up Postgres (postmaster) with the -i option.
You should also edit the pg_hba.conf file in the data dir to allow access from the foreign machine - pg_hba.conf allows you to configure the ip of the allowed connections, the type of authentication they should perform and what they acan access.
Also bear in mind that opening any tcp port is a potential security problem so its best done behind a firewall if you have to do it.
- Steve
