ssh error in syslog

[afterday]

Hi,

I getting

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

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

1. May I know it is ok to get  those message?
2. 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?

[Matti_Kurkela]

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.