[CentOS] CUPS oddity

[Laurent Wandrebeck]

2009/4/17 Niki Kovacs <contact at kikinovak.net>:
> Hi,
Hi,
>
> I've been setting up a few printer servers with CUPS. Our public
> libraries here all run 100% Linux (CentOS 5), so what I do is simply
> install the printer on one of the machines (with a static IP) and then
> configure CUPS so it can act as a printer server for Linux clients.
>
> It took me some time to figure this out, and I remember pulling my hair
> out for a few sunny afternoons, but I eventually got it working. One
> thing kept me stuck for days, until I finally found the answer on
> debian-administration.org.
>
> My server machine has an IP of 192.168.1.252/255.255.255.0. There's a
> Brother laser printer attached to it. The CUPS configuration file is
> edited so machines on the 192.168.1.* network can use it, and I can also
> access the CUPS web interface from anywhere. But here's what puzzles me.
>
> In the default cupsd.conf configuration file the 'Listen' directive
> looks like this:
>
> # Only listen for connections from the local machine.
> Listen localhost:631
> Listen /var/run/cups/cups.sock
>
> Here's the oddity: I *have* to specifically add the machine's IP, like this:
>
> Listen localhost:631
> Listen 192.168.1.252
> Listen /var/run/cups/cups.sock
>
> If I don't add this, machines on the network are unable to connect to
> the server.
>
> Can anybody explain this strange behaviour to me?
localhost is a non routable address: 127.0.0.1.
So it won't answer on the public ip address if you don't add it yourself.
Regards,
Laurent.