JDBC connection refused

I have Postgresql set up on RedHat 6.1, and I can access it with jdbc or
pgaccess locally, and with pgaccess from another linux box on the same
local net.  However, I can't get a connection with jdbc across the net.
The relevant code is
 public static void main (String[] args) {   try {     Class.forName("postgresql.Driver");     Connection con =
DriverManager.getConnection("jdbc:postgresql://birch/auction",        "collins", "");     // Do something useful here
 Statement stmt = con.createStatement();   ....
 

and the error message is

Connection refused. Check that the hostname and port is correct, and
that the postmaster is running with the -i flag, which enables TCP/IP
networking.at postgresql.Connection.openConnection(Connection.java, Compiled Code)
at postgresql.Driver.connect(Driver.java, Compiled Code)at java.sql.DriverManager.getConnection(DriverManager.java,
Compiled
Code)....

Here's what I've checked:- postmaster is indeed being run with the -i flag.  I think neither the
local jdbc or the remote pgaccess would work otherwise.  Here's the line
from rc.d/init.d/postgres:      su -l postgres -c '/usr/bin/postmaster -i -S -D/var/lib/pgsql'- I've used every name I
canthink of, including the ip address, in the
 
URL above.  I've used the port and I've not used the port.- I've used netstat to check that postmaster is indeed
listeningon
 
5432

I'm stumped.  Thanks in advance for any assistance.

John Collins
University of Minnesota