Subject: Re: failure from bizarre NAT setup
To: Steve Bellovin <smb@research.att.com>
From: Ian Lance Taylor <ian@wasabisystems.com>
List: tech-net
Date: 04/22/2004 07:33:21
Steve Bellovin <smb@research.att.com> writes:

> The hotel I'm currently staying at has a bizarre NAT+gateway that's 
> caused me an unusual problem: ssh and telnet die with 
> 
> 	"Can't assign requested address"
> 
> I suspect, but haven't proved, that the problem is related to messages 
> like this:
> 
>    fetchmail: gethostby*.getanswer: asked for "machshav.com IN AAAA", got type "A"
> 
> ssh is, I think, trying to get the local address, getting some bizarre 
> answer, and finding itself unable to bind to it.  I've bypassed the 
> problem by putting a BindAddress statement in my .ssh/config file, but 
> I shouldn't have to do that.  Rebooting worked yesterday, but that 
> feels very Windows-like: if your system doesn't work right, reboot and 
> see if that helps.  Ugh.
> 
> Does anyone have any clean suggestions on how to *fix* the problem?

I've had that problem at hotels before: they respond to an AAAA
request with an A answer.  Probably they respond to any request with
an A answer.

The only fix I've been able to come up with is to use direct IP
addresses.  Once I get the hotel to approve my connection (which for
me I usually have to do each time I un-suspend my laptop), I can
usually adjust /etc/resolv.conf to point to a reliable publically
accessible caching name server.  As an ex-Cygnus employee, I tend to
use ns.redhat.com for this purpose.

Ian