ATTN REDHAT (was Re: dns problems with ssh,telnet,ftp on a localnetwork)

[Alfredo Ferrari <list pceet030 cern ch>]

Hi,

thanks for the help, but I already have 

    order hosts,bind

inside /etc/host.conf. My setup is a "pure" RH7.2 with all updates,
however I have the feeling I hit a really weird bug in glibc, since I
found a thread in libc-alpha that explains exactly what the problem is, 
that is a bad behaviour of getaddrinfo which tries to get an Ipv6 
address as well even when a host is listed inside /etc/hosts
(see 
http://sources.redhat.com/ml/libc-alpha/2001-11/msg00125.html

and following...)

Now the question for RedHat: since this is really a tough problem, making 
in practice /etc/hosts completely useless and rendering simple local 
networks almost impossible to setup, are you going to provide some
patched stuff and/or good suggestions how to circumvent the problem?

I found the answers of Ulrich Drepper on this issue particularly
disappointing. Maybe he does not fully realize how it can badly break
everything (ssh,ftp,telnet etc) on a two-three machine isolated network
(typical home-like situation) when an external connection is not 
available (case two of
http://sources.redhat.com/ml/libc-alpha/2001-11/msg00153.html
)

                   Thanks
                ALfredo Ferrari


On Sun, 13 Jan 2002, Jan Carlson wrote:

> On Sun, Jan 13, 2002 at 03:53:23PM +0100, Alfredo Ferrari wrote:
> > Hi
> > 
> > I have two computers at home which talk over a twisted ethernet cable.
> > Till RH7.1, listing both machines inside their respective /etc/hosts
> > files was enough to make ssh,telnet,ftp work between them.
> > 
> > After upgrading to RH7.2 they do not longer work (I do not even reach the 
> > login prompt). With strace I can see that they try to reach the 
> > nameservers listed in /etc/resolv.conf which are unreachable most of the 
> > time (they are those of my ppp connection). Both /etc/hosts.conf and 
> > /etc/nsswitch.conf have the proper setting to use /etc/hosts in first p
> > lace, and ping and nfs mounts work flawlessly using the names as listed 
> > (and resolved) in /etc/hosts.
> > Furthermore strac'ing ssh shows that /etc/hosts is parsed, but apparently 
> > the resolver goes on trying also the nameservers listed in 
> > /etc/resolv.conf.
> > 
> > ssh,telnet,ftp'ing directly to the ip number works ok. It seems that these 
> > services are trying to make a further identification after parsing 
> > /etc/hosts which was not the case in the past. If I substitute 
> > /etc/resolv.conf with an empty one everything works ok, but of course 
> > I can no longer resolve names not in /etc/hosts when connected to the 
> > external world.
> 
> If you want the kernel to use a nameserver only if matching info is
> not in /etc/hosts, then keep the standard RH7.2 /etc/host.conf:
> 
> 	order hosts,bind
> 
> To contact foo.fun.com, you need the full "foo.fun.com" in /etc/hosts.
> 
> If this doesn't solve it, are you running anything besides the current
> Red Hat RH7.2 rpms?  Are there any tarballs installed?
> 
> 

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