ssh error in syslog

afterday — Fri, 06 Jan 2012 07:30:56 GMT

Hi,

I getting

sshd[18474]: channel_lookup: 0: bad id: channel free

sshd[18474]: Disconnecting: server_input_channel_req: unknown channel 0

May I know it is ok to get those message?
I have try google around, but cant get any information what does those message actually mean. Where can I get information on what does the message mean?

Re: ssh error in syslog

Matti_Kurkela — Mon, 09 Jan 2012 16:47:17 GMT

1.) Maybe someone is connecting to your sshd and sending it bad data (or really anything that is not valid SSH protocol data).

It might be because someone has made a mistake and configured some application to connect to a wrong port.

It might be an enterprise monitoring system that is trying to see if your sshd is still running.

It might be a malicious person, sending bad data to try and make your sshd crash or let the malicious person log in without valid authentication.

2.) Only two ways:

- read OpenSSH source code (available at www.openssh.com). The HP SSH is a port of OpenSSH.

- ask OpenSSH developers or other people who really know the internal workings of OpenSSH.