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Re: [Freeipmi-users] ipmiconsole sending unsollicited break

From: Fabien Wernli
Subject: Re: [Freeipmi-users] ipmiconsole sending unsollicited break
Date: Tue, 2 Apr 2013 10:52:39 +0200
User-agent: Mutt/1.5.21 (2010-09-15)


On Fri, Mar 29, 2013 at 10:49:48AM -0700, Albert Chu wrote:
> A) It seems you are using a console manager of some sort.  We use Conman
> here and have never seen this issue.  Is it possible the console manager
> is doing something to send the breaks/sysrqs?

We're using conserver. I seriously doubt the latter is to blame, as we've
never seen this using ipmitool.

> Note that I am aware of two console managers (Conman & Conserver) that
> have "native" IPMI console support via FreeIPMI's libipmiconsole
> library.  So if you use one of those, you wouldn't have to run
> 'ipmitool' or 'ipmiconsole' in a separate process.

Conserver doesn't support IPMI. Good to know Conman does, though.

> B) The default escape character in ipmiconsole is '&', which may not
> match with whatever the console manager wants to use or would expect?  I
> think ipmitool's is '~'.

Conserver uses a very long escape sequence, which is IMHO a good idea as it
reduces the chances to accidentally send a break sequence. As for our
previous setup, we were using '[' for the ipmitool sequence, but conserver
doesn't actually know/care about it. This being said, I don't think this is
relevant, as the SysRq were sent without anyone attached to the consoles,
so the break must have been sent internally, I guess.

> C) You note there was a lot of garbage when you switched from ipmitool
> to ipmiconsole.  It is possible (depending on many factors) that
> ipmiconsole was receiving packets from the previous ipmitool's console
> session.  The garbage is corrupted b/c ipmiconsole doesn't have the
> right information to decrypt the data.  This can have unexpected side
> affects.

This is what I was thinking, as ipmiconsole tries to stop the existing
connection. Maybe it wrongly assumes the latter is consumed by another
ipmiconsole process? Moreover, I think this is a bug: freeipmi really
shouldn't send data without any user input, should it?

> Do you continue to see this garbage on subsequent reboots?  If not, it
> may have been a one-time problem.

No, after reboot all was fine, although it lasted quite long as one of the
servers was found in the boot configuration screen of its RAID adapter. We
were lucky the garbage didn't reconfigure the ARRAY using random characters
(or the complete works of William Shakespeare for that matter).

> Those are just some ideas.

Thanks for looking into this. Maybe there is some evidence in the routine
handling the disconnection in the code.

Oh, and the two servers this happened on were IBM (3550 and 3650).


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