Another issue with pg_hba.conf file & dumpall

Can't thank you all enough for the help.  :-)

Here's another problem I'm having.  I'm using pg_dumpall
in a micro sized perl script to dump the entire db cluster.
(All it did was save the password to an environment variable,
and modified the backup file's name to include the date.)

This script has been working on our old server for over a
year.  We're trying to get it to work with our new one, but
with stricter security measures.  (Our older one used ident,
which our boss has now banned for the new one.)  Unfortunately,
I'm getting the following message back when trying to run it
manually:

pg_dump: [archiver (db)] connection to database "db1" failed: FATAL:
No pg_hba.conf entry for host localhost, user postgres, database db1

and dies on the first database:

pg_dumpall: pg_dump failed on db1, exiting


The script is owned by postgres, pg_dumpall is owned by postgres,
and is being run as user postgres with postgres' environment
variables (i.e., su - postgres before execution.).  So if it is
a permissions issue with a file, it isn't obvious.

Here's part of my pg_hba.conf file:

local       template1    postgres                               md5
local       template1         all                               reject
host        all          postgres    127.0.0.1    255.0.0.0     md5
hostssl     template1         all    0.0.0.0      0.0.0.0       reject

line #3 should be the one that pg_dumpall should be using.

What am I doing wrong?  The docs give examples, but not enough
to get a handle on this problem.

Again, any help would be greatly appreciated.

April Carvalho