Re: SSH: Syslog: Protocol Error

From: Richard E. Silverman (res_at_qoxp.net)
Date: 02/24/04 

Date: 24 Feb 2004 14:29:54 -0500

>>>>> "AK" == Andy K <akarseras@yahoo.com> writes:

    AK> Hi, I have written a basic application which automatically
    AK> transfers files from one node to another using SFTP.

    AK> All works well for approx. 8 hours when the script halts and I see
    AK> the following entry in the syslog:-

    AK> sshd[22993]: Disconnecting: Protocol error: expected packet
    AK> type 30, got 20

    AK> If I restart the application all works well for another 8-9 hours
    AK> when I encounter the same problem.

    AK> I am using OpenSSH_3.6.1p2 on an HP-UX 11.11 box.

On the client? Server? Both?

    AK> Could anybody shed some light on what this error may mean ?

from ssh2.h:

#define SSH2_MSG_KEXINIT 20
#define SSH2_MSG_KEX_DH_GEX_REQUEST_OLD 30

So, this suggests it's a problem with rekeying. The connection is
re-keyed after a certain amount of time elapses or data is transferred,
which would explain why it happens after the process has been running for
a while.

If you read the ChangeLog, you'll find there was bugfixing activity
regarding rekeying around version 3.6.1. So, even without knowing exactly
what's going on, this strongly suggests you a) try turning off rekeying
for a quick fix, and b) upgrade to see if the problem is fixed.

I think you must be using something other than OpenSSH_3.6.1 on one side,
because I think that version did not automatically initiate rekeying from
either side, only respond to rekeying requests from other
implementations. If that's the case, try turning off rekeying on the
other side. 

-- 
  Richard Silverman
  res@qoxp.net