[atoav]

Another thing that can be useful is to use tcpdump on the other side to see if the stuff sent to e.g. a TCP port is actually received:

  tcpdump -i any src port 5432 or dst port 5432

If it is now received you know you need to investigate on your receiving side, if it is not, the problem might be firewall or network.

[justinsaccount]

that is the same as

  tcpdump -i any port 5432