Remote connection through ODBC

Dear all

I am a newbie using PostgreSQL, for instance through ODBC. I have troubles with the remote connection through ODBC. I have a PostgreSQL 9.1 instance on an Ubuntu 13.04, a client on a Centos 6.4.

ODBC driver on the CentOs machine is the standard one shipped in the CentOS repo, version 08.04.0200.

I have no problem to connect locally to the PostgreSQL from the Ubuntu machine. However, when I try an isql query from the Centos client, i get
[ISQL]ERROR: Could not SQLConnect.

Note that the file postgresql.conf contains a listen_adresses='*', and pg_hba.conf contains the line
host all all 0.0.0.0/0 md5

On the other hand, I have no problem to connect through pgadmin3 from the CentOS machine. As well with the psql commant : it works.

At the end, I am interested in querying the database from a C code : of course it does not work

File obc.ini contains correct credentials (and a connection to a MySQL server works)

Any help would be much appreciated !

Benjamin.