[vox-tech] telnet daemon doesn't work

[Nick Schmalenberger]

On Sun, Apr 04, 2010 at 11:02:09PM -0700, Brian Lavender wrote:
> Wierd thing is that if I run a simple echo server on that port, it
> works.
>
The tcp6 just means that is using an ipv6 socket, but it can
still accept ipv4 connections using an ipv4 mapped address. I
suppose the talk by Owen DeLong from Hurricane Electric in July
will demonstrate this. How I would troubleshoot this, is run
tcpdump to see if the traffic is coming in. Then, see if there
are any rules in the INPUT chain in iptables that might be
blocking it (or in the FORWARD chain in the dom0, and you can run
tcpdump on peth0 and the vif interface also to see both sides of
the xen bridge/iptables FORWARD chain). But you said it works
with the echo server, so I guess the traffic is coming into the
domU. If its passing through iptables in the domU, then you could
try running netcat on the telnet port with telnet negotiation
instead, or telnetd (there are various ones, maybe some have
easier troubleshooting?) with debugging turned on and not daemonizing
so you can see more output about if it is configured correctly.
Anyway, maybe those steps are kind of out of order with regard to
how the traffic goes up the network stack but it should be with xen:
physical ethernet->iptables FORWARD->dom0 vif->
domU eth0->iptables INPUT->user process network socket
I hope that makes sense.
Nick Schmalenberger