Reading documentation at Postgresql.org
http://www.postgresql.org/docs/9.2/static/auth-pg-hba-conf.html
I would suggest changing the user field with the names of several users who are allowed to remotely connect:
host all john,charles 0.0.0.0/0 md5 host all john,charles ::1/128 md5
In addition, for security reasons, I would advise you to study the use of "hostssl", as well as specify the name of the database, which can be accessed remotely:
hostsll webapp123 john,charles 0.0.0.0/0 md5
And if remote access is available only from certain computers, specify their static IP addresses (if using DHCP, use the mask accordingly.)
hostsll webapp123 john,charles 1.2.3.4/32 md5
Thus, you only jeopardize the webapp123 database, to what users john and charles can do, and only from computer 1.2.3.4.
As mentioned in the documentation, you can have any number of entries, so if you want to add a test server (i.e. your server at home), you can add one line to make it look like this:
hostsll webapp123 john,charles 1.2.3.4/32 md5 hostsll webapp123 henry home-ip/32 md5
Without specifying users, you probably allow any user, including without passwords, and one of them is selected and works ...
Of course, I would strongly advise you not to name a user who has administrator rights in your database unless you specify its static IP address.