Indirect XDMCP doesn't work

[Derek Broughton]

Jonas Norlander wrote:

>> I found it. This is actually a bug:
>> https://bugs.launchpad.net/bugs/86021
>> Changing the 127.0.1.1 line in /etc/hosts on the XDMCP server made it
>> work.
>>
> 
> I don't get that. Why do they add that line? Is only so you can ping
> your hostname? I don't think there are any services listening on
> 127.0.1.1.

You could ping your hostname if it was aliased to 127.0.0.1, too (and
really, your hostname should be aliased to _something_).

I'm not sure of your point, but any services listening on "localhost" are
listening on 127.0.1.1.  By default, it's true, no services are listening
on localhost.  But in my case, Apache pays attention to 127.0.0.1,
127.0.1.1, 127.0.2.1, 127.0.2.2, and 127.0.2.3 individually.

$ ifconfig lo
lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0

So, any address beginning 127.* goes through the lo interface.  I don't know
if XDMCP can then differentiate between the destinations as Apache can, but
it can be very useful.

"Why do they do that"?  Because it's useful.
"Can it cause problems"?  Not to somebody who knows what they're doing, and
XDMCP is very much an edge case amongst ubuntu users these days.
-- 
derek