Cannot connect to postgres from remote host

Is the firewall letting the connections through? Or, check if pg_hba.conf allows connecting from addresses other than localhost.

Check the setting of listen_addresses in your postgresql.conf file. Many distributions make it default to 127.0.0.1, i.e. listen only to connections coming in from localhost. It should be set to '*' to listen for connections on all interfaces.

If you are still having trouble, use lsof to see what network sockets the postgres process is listening on.

On Ubuntu, I noticed that remote access at some point stopped working (currently using 9.1.9). The reason is, that postgres is no longer started with the -i switch [1] so no matter what you configure for listen_addresses, it will be ignored.

Fortunately, adding the following line to /etc/environment solves the problem after logging out and in again (or reboot):

PGOPTIONS="-i"

See [2] for more options. Note, that adding this to /etc/postgresql/9.1/main/environment did NOT work for me.

Now, when doing nmap ip-of-my-remote-server I finally get this again:

5432/tcp open  postgresql

Yay!

[1] http://www.postgresql.org/docs/9.1/static/runtime-config-short.html

[2] http://www.postgresql.org/docs/9.1/static/libpq-envars.html

The listen_address configvar in postgresql.conf is not the only way to get postgres to listen on the non-local IP-address (or addresses).

Use option "-o -h *" if you start postgres from pg_ctl, otherwise do add "-h" "*" to the postgres command line, like e.g.

/usr/local/pgsql/bin/postgres -D /pg/data "-h" "*"

Of course /pg/data must be changed to your current datapath.

This is especially useful when experimenting.