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Re: [Xen-API] Problem connecting to xcp via xencenter or ssh

  • To: xen-api@xxxxxxxxxxxxx
  • From: Alexandre Kouznetsov <alk@xxxxxxxxxx>
  • Date: Wed, 13 Mar 2013 10:59:39 -0600
  • Delivery-date: Wed, 13 Mar 2013 17:00:23 +0000
  • List-id: User and development list for XCP and XAPI <xen-api.lists.xen.org>


El 13/03/13 02:27, Joseph-Andre Guaragna escribió:
We installed xcp on a dell T410 which uses broadcom netXtreme II BCM
5716 NIC cards, and experienced problems connecting to it whether
using  xencenter or ssh.
With  Xencenter we get a first connection then after few secon we are
disconnected and cannot acces it anymore.
We tryed then to connect it via ssh, got a connection refused. However
we did ping the machine at every step.

Please consider this debugging steps:

Check general logs, dmesg and console output of your XCP for strange events.

Make sure, the problem is XCP related. Boot your T410 from some LiveCD and test SSH connectivity. This is a high level of abstraction test, but it worth it, at least it would allow you to discard general hardware and network problems.

Run your SSH client in verbose mode (-v or -vv or -vvv). Maybe it will tell you something interesting on disconnect.

Modify XCP's SSHd config to increase logging level (LogLevel directive). For reference, you may try to do the same on a known working machine, so you may compare the logs and distinguish between usual evens and the unusual ones.

Check with tcpdump if something strange is going on your network. Consider using -e flag, so the MAC addreses of the packets are shown, that often helps to detect routing and IP configuration problems.

Carefully inspect current netfilter configuration (iptables -L -v). Test setting it in "wide open" mode and try to connect again:
iptables -P INPUT   ACCEPT
iptables -P OUTPUT  ACCEPT
iptables -F -t nat
iptables -X -t nat
iptables -F -t filter
iptables -X -t filter
iptables -F -t mangle
iptables -X -t mangle
iptables -F -t raw
iptables -X -t raw
iptables -Z
Make sure you do this while your server is connected to a secure network.

Note that none of this steps are supposed to be a solution to whatever the problem is, but they might give a clue of what is the problem's nature is.


Alexandre Kouznetsov

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