No pg_hba.conf entry

Hello,

When I try to connect via JDBC to PostgreSQL I get the following error
message:

Error -- Something unusual has occured to cause the driver to fail.
Please report this exception:
java.sql.SQLException: No pg_hba.conf entry for host 143.233.73.254,
user aaa, database bbb

However, the only lines in pg_hba.conf that are not commented out are:

local        all                                         trust
host         all         127.0.0.1     255.255.255.255   trust
host         all         143.233.73.0  255.255.255.0     trust

Isn't this strange? I tried this with both jdbc6.5-1.2.jar and
jdbc7_0-1_2.jar from 143.233.73.254 which runs Linux and from my WinNT
4.0 (sp6) machine and for different databases.

I use PostgreSQL 6.5.2 and before you ask, yes postmaster runs with the
-i option set.

Any comments will be more than welcome.