I dont understand host connections

I am trying a host connection but to no avail.  In postgresql.conf I
have tcpip_socket = true and port = 5432.  In pq_hda.conf I have 

host     all      0.0.0.0     0.0.0.0      md5       optix.conf

with two users in optix.conf.  Efforts to log in fail:

$ psql -U thad optix
psql: FATAL 1:  No pg_hba.conf entry for host localhost, user thad,
database optix

But if I put 

local      all                             md5      optix.conf

in pg_hda.conf and restart PostgreSQL, I'm prompted for a password and
can log in.

I'm running PostgreSQL 7.2.2. on an RedHat 6.2 machine.
-- 
------------------------------------------------------------------------
Thad Humphries              "...no religious test shall ever be required
Web Development Manager      as a qualification to any office or public
Phone: 540/675-3015, x225    trust under the United States." -Article VI