Proper remote access control management in PostgreSQL I want to create environment that allows the limited number of machines connect to my database server. 
For debugging needs all IP address have the remote access to PostgreSQL server 

listen_addresses = '*'
host all all 0.0.0.0/0 md5


I want to limit access. What is the canonical way to do that?
I though of using proxy server to connect from local machines to PostgreSQL server, but I'll appreciate other ideas.
Just change pg_hba.conf from 

host all all 0.0.0.0/0 md5


to rules you need. Columns are :
type (leave host),
database,
username,
IP,
access method.
For example, if you need to allow only 1.2.3.4 and 5.6.7.8 to connect any database using any username:

host all all 1.2.3.4/32 md5
host all all 5.6.7.8/32 md5
host all all 0.0.0.0/0 reject


Use
    service postgresql reload 
(or smt like that, depending on your system) to apply changes.