Snort mailing list archives
Re: ssh: Protocol mismatch
From: Eoin Miller <eoin.miller () trojanedbinaries com>
Date: Mon, 07 Dec 2009 15:43:44 -0500
FYI, I've seen the same thing happens when using PuTTY as a client from a windows box. -- Eoin Griffin, Chris Andrew (Chris) wrote:
Guys, I just re-activated my sensor after a period of inactivity (mysql db machine was down). Preprocessors are enabled including the (experimental?) ssh preprocessor. preprocessor ssh: server_ports { 22 } \ max_client_bytes 19600 \ max_encrypted_packets 20 \ enable_respoverflow enable_ssh1crc32 \ enable_srvoverflow enable_protomismatch I started two SSH2 sessions from a HOME_NET Windows XP PC (Secure CRT 4.0.1) to the Slackware 12.1 system running snort (Version 2.8.5.1 (Build 114)). It is OpenSSH_5.1p1 forcing "Protocol 2". I ended up getting 194 alerts labeled "ssh: Protocol mismatch". As far as I know my connection was a "clean" two-way traffic exchange. All the alerts are pertaining to the SSH Client -> SSH Server packets, though this makes some sense considering what I read about the protocol mismatch. I tried another session from a !HOME_NET PC with another "clean" session and before I typed anything at the command prompt I had 58 alerts. The odd thing is I wouldn't expect a protocol mismatch to be triggered in this case? I can't find much in the docs about how this alert works, but from what I gather it's when a non-SSH packet is sent to an SSH server on SSH_PORT (22)? Also README.ssh says "The Secure CRT and protocol mismatch exploits are observable before the key exchange." but I believe a lot of the packets triggering this alert may not be before the key exchange, but I'm definitely no SSH expert. Thoughts? Does this sound like a problem? or do I misunderstand how this works? Chris Griffin ------------------------------------------------------------------------------ Join us December 9, 2009 for the Red Hat Virtual Experience, a free event focused on virtualization and cloud computing. Attend in-depth sessions from your desk. Your couch. Anywhere. http://p.sf.net/sfu/redhat-sfdev2dev _______________________________________________ Snort-users mailing list Snort-users () lists sourceforge net Go to this URL to change user options or unsubscribe: https://lists.sourceforge.net/lists/listinfo/snort-users Snort-users list archive: http://www.geocrawler.com/redir-sf.php3?list=snort-users
------------------------------------------------------------------------------ Join us December 9, 2009 for the Red Hat Virtual Experience, a free event focused on virtualization and cloud computing. Attend in-depth sessions from your desk. Your couch. Anywhere. http://p.sf.net/sfu/redhat-sfdev2dev _______________________________________________ Snort-users mailing list Snort-users () lists sourceforge net Go to this URL to change user options or unsubscribe: https://lists.sourceforge.net/lists/listinfo/snort-users Snort-users list archive: http://www.geocrawler.com/redir-sf.php3?list=snort-users
Current thread:
- ssh: Protocol mismatch Griffin, Chris Andrew (Chris) (Dec 07)
- Re: ssh: Protocol mismatch Eoin Miller (Dec 07)
- Re: ssh: Protocol mismatch Ryan Jordan (Dec 16)
- Re: ssh: Protocol mismatch Griffin, Chris Andrew (Chris) (Dec 21)
- Re: ssh: Protocol mismatch Ryan Jordan (Dec 16)
- Re: ssh: Protocol mismatch Eoin Miller (Dec 07)