Re: [Vserver] localhost oddity on vserver host

From: Herbert Poetzl <herbert_at_13thfloor.at>
Date: Mon 03 Jul 2006 - 16:37:38 BST
Message-ID: <20060703153737.GE25534@MAIL.13thfloor.at>

On Mon, Jul 03, 2006 at 10:35:44AM -0400, Paul S. Gumerman wrote:
> Herbert,
>
> This problem is on the *host*, not a guest.
>
> I've verified that none of the guests on vhost3 (the box with the
> problem) has anything to do with 127.0.0.1.
>
> Also, on vhost3, sshd with explicit "ListenAddress" settings for the
> host's ip as well as 127.0.0.1 will start and run without complaining
> that it cannot bind to 127.0.0.1, but netstat doesn't show it listening
> on localhost.
>
> For the life of me, I cant figure this out ...
>
> On vhost1 (the working box):
>
> [root@vhost1 ~]# ping 127.0.0.1
> PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data.
> 64 bytes from 127.0.0.1: icmp_seq=0 ttl=64 time=0.039 ms
> 64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.018 ms
> 64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.033 ms
>
> --- 127.0.0.1 ping statistics ---
> 3 packets transmitted, 3 received, 0% packet loss, time 2010ms
> rtt min/avg/max/mdev = 0.018/0.030/0.039/0.008 ms, pipe 2
>
> On vhost3 (the troublesome box):
>
> [root@vhost3 etc]# ping 127.0.0.1
> PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data.
> <hit cntrl-C here>
> --- 127.0.0.1 ping statistics ---
> 6 packets transmitted, 0 received, 100% packet loss, time 4999ms
>
> Any thoughts?

the following things come to my mind:

 - iptables/tc rules blocking 127.0.0.1
 - special routing tables (with strange priorities)
 - loopback itnerface not properly configured
 - kernel bug (different kernel version)

HTH,
Herbert

> Paul
>
> Herbert Poetzl wrote:
>
> >On Fri, Jun 30, 2006 at 08:51:58PM -0400, Paul S. Gumerman wrote:
> >
> >
> >>In it's own thread now -- sorry for the unintentional hijack.
> >>
> >>I have two practically identical vserver hosts, named vhost1 and vhost3.
> >>
> >>They are both running kernel CentOS (2.6.14.3-vs2.0.1-rc5) x86_64.
> >>
> >>/etc/hosts on each one is essentially the same, and the routes look
> >>good and essentially the same.
> >>
> >>The ifconfig output for both looks the same, and both show traffic in
> >>and out of lo.
> >>
> >>
> >
> >this suggests that you 'assigned' some loopback ip
> >(probably 127.0.0.1) to both guests, which will them
> >allow to bind to that ip too
> >
> >this very likely results in two guests competing for
> >that address, so some services will be able to bind
> >others will fail ...
> >
> >
> >
> >>On vhost1, "ping 127.0.0.1" works as expected, and sshd can listen on
> >>the localhost port 22, and can be used there (by freenx).
> >>
> >>On vhost3, "ping 127.0.0.1" *sends* packets, but shows 100% packet
> >>loss. Also, sshd does not complain about listening on localhost,
> >>but it doesn't show up in netstat's output, and it doesn't work on
> >>localhost (freenx fails).
> >>
> >>Does anybody have any ideas? Unfortunately, vhost3 is a hundred miles
> >>away, and one of the virtual servers is running an important mail
> >>server, so I have to be careful. But vhost1 is here, and not so
> >>critical, so I can experiment with it.
> >>
> >>
> >
> >basically I do not see a good reason for assigning
> >127.x.x.x to a guest, but if you have to, then try
> >to choose different ones, e.g. 127.0.0.2, 127.0.0.3 ...
> >
> >HTH,
> >Herbert
> >
> >
> >
> >>Thanks,
> >>Paul
> >>
> >>
> >
> >
> >
> >>_______________________________________________
> >>Vserver mailing list
> >>Vserver@list.linux-vserver.org
> >>http://list.linux-vserver.org/mailman/listinfo/vserver
> >>
> >>
> >
> >
> >
> >
> >
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Received on Mon Jul 3 16:40:01 2006

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