Re: [Xen-users] ssh issues on DomU

[Andrew McGlashan <andrew.mcglashan@xxxxxxxxxxxxxxxxxxxxx>]

Hi,

Heiko Wundram wrote:
> > > Do you have any firewall in place that might be dropping connections ?
> > No, the closest thing would be the standard iptables rules on Dom0 ...
> > but it looks "okay" to me.
> It isn't.
>
> > Chain FORWARD (policy DROP)
> > target     prot opt source               destination
> > ACCEPT     all  --  anywhere             anywhere            state
> > RELATED,ESTABLISHED PHYSDEV match --physdev-out vif3.1
> > ACCEPT     all  --  anywhere             anywhere            PHYSDEV
> > match --physdev-in vif3.1
> > ACCEPT     all  --  anywhere             anywhere            state
> > RELATED,ESTABLISHED PHYSDEV match --physdev-out vif3.0
> > ACCEPT     all  --  anywhere             anywhere            PHYSDEV
> > match --physdev-in vif3.0
> > ACCEPT     all  --  anywhere             anywhere            PHYSDEV
> > match --physdev-in peth1
> These rules basically say that any traffic coming in from anywhgere (the
> outside) and being directed towards your DomU is only valid if it is
> part of an existing connection (see the state RELATED,ESTABLISHED on the
> physdev-out matches, which are driven by the stateful xtables match of
> the Dom0 kernel), whereas the DomU is allowed to do any traffic (see the
> physdev-in match).
The DomU machine can host a website, no problem.  It can reply to pings 
sent to it by another machine on the 192.168.1.0 network just fine.
ssh works fine for the 192.168.10.201 going through Dom0 in the same 
manner as http [modem / forwarding -- modem is on 192.168.10.0 network].
So, ssh is different from _other_ traffic types for some reason.

> The Dom0 is allowed to do traffic to all DomUs, because the packets the
> Dom0 generates go through INPUT and OUTPUT, but not through FORWARD. You
> might want to check the iptables generation on your Dom0.
I didn't craft the iptables rules on Dom0, it is standard installation 
with bridged networking setup -- okay, I had to mod the network script 
for xen, but I didn't fiddle with any iptables rules.
--
Kind Regards
AndrewM

Andrew McGlashan
Broadband Solutions now including VoIP


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