[cups.general] cupsd no longer allows using cname (alias) must use hostname

[Michael Sweet]

You are running into the (relatively new) DNS rebinding attack protection code. Sadly, while we do our best at startup we don't always catch all of the aliases for a given server. To work around this, add ServerAlias directives to your cupsd.conf file, either the "allow anything" version:

    ServerAlias *

or one per hostname, e.g.:

    ServerAlias name1.example.com
    ServerAlias name2.example.com
    ServerAlias name3.example.com

On Mar 13, 2011, at 5:39 PM, scott henry wrote:

> I was running debian Lenny on my server, and had a hostname alias (CNAME) setup
> using dnsmasq (since I had to move the printer around, it was easier to
> move the alias than to change the /etc/cups/client.conf on every other computer
> on the network). Lenny was running version 1.3.8. I upgrade the server to
> debian Squeeze, which is running cups v1.4.4, and I can no longer use the
> alias to access the printer server, I must use the hostname of the server.
> If I use the hostname, things work:
> 
> $ lpstat -h filess:631 -t
> scheduler is running
> system default destination: hp940c
> device for hp940c: usb://HP/DESKJET%20940C?serial=XXXXXXXXXXXXX
> device for PDF_to_file: cups-pdf:/
> hp940c accepting requests since Sun Oct 28 12:27:34 2007
> PDF_to_file accepting requests since Wed Oct  3 11:28:25 2007
> printer hp940c is idle.  enabled since Sun Oct 28 12:27:34 2007
> printer PDF_to_file is idle.  enabled since Wed Oct  3 11:28:25 2007
> 
> $ lpstat -h print:631 -t
> scheduler is running
> no system default destination
> lpstat: Bad Request
> lpstat: Bad Request
> lpstat: Bad Request
> lpstat: Bad Request
> lpstat: Bad Request
> 
> And I get similar bad behavior on other commands or using the web admin
> (note that the server is headless). All of the machines on this network
> are Linux or Mac OSX.
> 
> The error_log file shows:
> E [13/Mar/2011:17:31:22 -0700] Request from "192.168.55.24" using invalid Host: field "print"
> however that is a valid CNAME for the host, and it works for every other use.
> 
> Is this a configuration error on my part? I can't find anything about this
> in the docs or searching this site, though I might be looking for the wrong
> thing. I want my old behavior back!
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________________________________________________________________________
Michael Sweet, Senior Printing System Engineer, PWG Chair