Libguestfs - Nov 2014 - Re: virt-v2v: Died at /usr/bin/virt-p2v-server line 411

Le 19/11/2014 18:12, Richard W.M. Jones a écrit :
> On Wed, Nov 19, 2014 at 04:42:23PM +0100, Nicolas Ecarnot wrote:
>> disks:
>> 	nbd:localhost:33363 (raw) [sda]
>> 	nbd:localhost:49584 (raw) [sdb]
>> 	nbd:localhost:41988 (raw) [sdc]
>> removable media:
>>
>> NICs:
>>
>> [   0.0] Creating an overlay to protect the source from being modified
>> qemu-img create -q -f qcow2 -b 'nbd:localhost:33363' -o
>> 'compat=1.1,backing_fmt=raw' /var/tmp/v2vovl636444.qcow2
>> nbd.c:nbd_receive_negotiate():L501: read failed
>> qemu-img: /var/tmp/v2vovl636444.qcow2: Could not open
>> 'nbd:localhost:33363': Could not open image: Invalid argument:
>> Invalid argument
>
> What is supposed to happen is that qemu-nbd is started (3 times) on
> the virt-p2v machine.  Then 3 x ssh connections are made which reverse
> proxy the nbd connection from virt-v2v back to virt-p2v, the
> equivalent of:
>
>    ssh -R 33363:localhost:<hostport> virt-v2v-server
>
> Somehow that's not happening.
>
> I'm not sure what.  Is this reproducible?  Do you have an unusual
> firewall configuration on the virt-v2v conversion server?
>
> Rich.
>
It is 100% reproductible.

Your interesting comment lead me to keep a better look at 
/var/log/secure on the conversion server :

The "test" button succeed in connecting. I see it in the logs.

Nov 19 21:48:23 serv-p2v-adm1 sshd[2654]: Accepted password for root 
from 192.168.49.5 port 36574 ssh2
Nov 19 21:48:23 serv-p2v-adm1 sshd[2654]: pam_unix(sshd:session): 
session opened for user root by (uid=0)
Nov 19 21:48:23 serv-p2v-adm1 sshd[2654]: Received disconnect from 
192.168.49.5: 11: disconnected by user
Nov 19 21:48:23 serv-p2v-adm1 sshd[2654]: pam_unix(sshd:session): 
session closed for user root

Here I wait on purpose a long time to distinguish what is happening in 
the log files.
I'm filling in the different fields in the conversion screen, the I 
launch the conversion, and I see that :

(192.168.49.5 is the source machine)

Nov 19 21:54:52 serv-p2v-adm1 sshd[2725]: Accepted password for root 
from 192.168.49.5 port 36575 ssh2
Nov 19 21:54:52 serv-p2v-adm1 sshd[2725]: pam_unix(sshd:session): 
session opened for user root by (uid=0)
Nov 19 21:54:52 serv-p2v-adm1 sshd[2727]: Accepted password for root 
from 192.168.49.5 port 36576 ssh2
Nov 19 21:54:52 serv-p2v-adm1 sshd[2727]: pam_unix(sshd:session): 
session opened for user root by (uid=0)
Nov 19 21:54:53 serv-p2v-adm1 sshd[2725]: channel 2: open failed: 
connect failed: Connection refused
Nov 19 21:54:53 serv-p2v-adm1 sshd[2727]: Received disconnect from 
192.168.49.5: 11: disconnected by user
Nov 19 21:54:53 serv-p2v-adm1 sshd[2725]: Received disconnect from 
192.168.49.5: 11: disconnected by user
Nov 19 21:54:53 serv-p2v-adm1 sshd[2725]: pam_unix(sshd:session): 
session closed for user root
Nov 19 21:54:53 serv-p2v-adm1 sshd[2727]: pam_unix(sshd:session): 
session closed for user root

Indeed, I see "Connection refused".
Let's investigate on this.

On the conversion server (serv-p2v-adm1), before running all this, I did 
a "iptables -F" (and a restart of NFS - not knowing if it was needed),
so I have no rule in iptables now.

Do I have to find a way to increase the verbosity of sshd in 
/var/log/secure?

Another point : as I wrote it before, I have no way to get a shell 
prompt on the source machine, because alt-F1 leads to a blinking screen 
trying to run virt-p2v and failing and respawning.
I nmap'd this source host, and saw that ssh was open.
In order to run the action step by step, is there a way to connect to 
this root account? What password? (already tried 
secret/p2v/root/password/PASSWORD/redhatrulez but that did not the trick)

Regards,

-- 
Nicolas Ecarnot

On Wed, Nov 19, 2014 at 10:05:53PM +0100, Nicolas Ecarnot
wrote:
> Nov 19 21:54:52 serv-p2v-adm1 sshd[2727]: pam_unix(sshd:session):
> session opened for user root by (uid=0)
> Nov 19 21:54:53 serv-p2v-adm1 sshd[2725]: channel 2: open failed:
> connect failed: Connection refused
> Nov 19 21:54:53 serv-p2v-adm1 sshd[2727]: Received disconnect from
> 192.168.49.5: 11: disconnected by user
> Nov 19 21:54:53 serv-p2v-adm1 sshd[2725]: Received disconnect from
> 192.168.49.5: 11: disconnected by user
[...]
>
> Indeed, I see "Connection refused".
> Let's investigate on this.
> 
> On the conversion server (serv-p2v-adm1), before running all this, I
> did a "iptables -F" (and a restart of NFS - not knowing if it was
> needed), so I have no rule in iptables now.
> 
> Do I have to find a way to increase the verbosity of sshd in
> /var/log/secure?
You might want to check that sshd allows port forwarding
('AllowTcpForwarding yes' in /etc/ssh/sshd_config).

It would be useful to know what the actual sshd failure is.

This is how ssh is invoked on the virt-p2v side:

https://github.com/libguestfs/libguestfs/blob/master/p2v/ssh.c#L174
plus
https://github.com/libguestfs/libguestfs/blob/master/p2v/ssh.c#L595
> Another point : as I wrote it before, I have no way to get a shell
> prompt on the source machine, because alt-F1 leads to a blinking
> screen trying to run virt-p2v and failing and respawning.
> I nmap'd this source host, and saw that ssh was open.
> In order to run the action step by step, is there a way to connect
> to this root account? What password? (already tried
> secret/p2v/root/password/PASSWORD/redhatrulez but that did not the
> trick)
I'm fairly sure the root account is disabled, and sshd isn't supposed
to be running, but apparently it is (a bug).  It's also a bug that
there is no shell on another other virtual console, but TBH I don't
know how to fix that ...

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-top is 'top' for virtual machines.  Tiny program with many
powerful monitoring features, net stats, disk stats, logging, etc.
http://people.redhat.com/~rjones/virt-top

Le 19/11/2014 22:19, Richard W.M. Jones a écrit :
> On Wed, Nov 19, 2014 at 10:05:53PM +0100, Nicolas Ecarnot wrote:
>> Nov 19 21:54:52 serv-p2v-adm1 sshd[2727]: pam_unix(sshd:session):
>> session opened for user root by (uid=0)
>> Nov 19 21:54:53 serv-p2v-adm1 sshd[2725]: channel 2: open failed:
>> connect failed: Connection refused
>> Nov 19 21:54:53 serv-p2v-adm1 sshd[2727]: Received disconnect from
>> 192.168.49.5: 11: disconnected by user
>> Nov 19 21:54:53 serv-p2v-adm1 sshd[2725]: Received disconnect from
>> 192.168.49.5: 11: disconnected by user
> [...]
>>
>> Indeed, I see "Connection refused".
>> Let's investigate on this.
>>
>> On the conversion server (serv-p2v-adm1), before running all this, I
>> did a "iptables -F" (and a restart of NFS - not knowing if it
was
>> needed), so I have no rule in iptables now.
>>
>> Do I have to find a way to increase the verbosity of sshd in
>> /var/log/secure?
>
> You might want to check that sshd allows port forwarding
> ('AllowTcpForwarding yes' in /etc/ssh/sshd_config).
This is the next thing I tried after posting my previous reply.
It was commented, and the man page says it is enable by default.
Anyway, I forced it on yes, restarted sshd and tried again but with no 
success.

I'm trying the same operation after increasing the sshd log verbosity.

-- 
Nicolas Ecarnot