Trouble Catching "Received packet SSH_MSG_UNIMPLEMENTED"

0 votes
asked Nov 16, 2015 by Henry27 (120 points)

ERROR sshK(2)[15] SSH: Rebex.Net.SshException: Requested service is not implemented.
at Rebex.Net.SshSession.XY(Byte[] A, Int32 B, Int32 C)
at Rebex.Net.SshSession.WY(Byte[] A, Int32 B, Int32 C)
at Rebex.Net.SshSession.VY(RGB A, Object[] B)
at Rebex.Net.SshChannel.YB(Boolean A)
at Rebex.Net.SshChannel.FC(Int32 A, SocketSelectMode B)

Hi,

I am having some trouble catching SSH_MSG_UNIMPLEMENTED packets from SSH servers. This trouble occurs when the terminal control is sent this packets from the ssh server. The event ends up unhandled and causes the usual havoc.

This packet is sometimes sent by Cisco ASA firewalls while they are pinging an unreachable destination.

As best as I can tell, the event could be handled by Terminal Event "ProcessingError". But it's not. Could you please help clarify how this event can be caught for proper handling.

Using
Rebex SSH Pack for .NET
Release 2015 R4.1 released 2015-08-24
Visual Basic 2013

Issue observed on Cisco ASA OS 8.2 and 9.1 but likely occurs with all versions.

Thanks,
H.

1 Answer

0 votes
answered Nov 17, 2015 by Lukas Pokorny (85,170 points)

Hi, SSH_MSG_UNIMPLEMENTED packets are supposed to be sent by the SSH server in response to messages it does not recognise. During normal operation of Rebex SSH Pack, this should never occur.

Unfortunately, we don't have enough information on this case yet and are unable to tell what exactly is going on and whether those errors should cause ProcessingError event to be raised. Could you please use Ssh object's LogWriter property to create a communication log and either post it here or mail it to support@rebex.net for analysis? Thanks!

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