Snort mailing list archives
port number or'ing
From: "Craig Mueller" <cmueller () alebra com>
Date: Thu, 22 Jan 2004 12:51:41 -0600
I'd like to write a rule that detects any inbound TCP connection, that alerts when the dest port != a defined set of ports. Example: Allowed inbound TCP ports is 25, 80, 443. If a connection attempt to any port not in the list, then alert. Resulting in a connection attempt to 22 triggers alert..
Currently I use a rule in this form, to look for TCP port 25 alert tcp $EXTERNAL_NET any -> $HOME_NET !25 (msg:" TCP port TCP !25"; classtype:Critical;) I know this does not work, but I think something this could work: alert tcp $EXTERNAL_NET any -> $HOME_NET ![25,80,443] (msg:" TCP port TCP !25,80,443"; classtype:Critical;) Thanks -- Craig Mueller CISSP Senior Consultant Alebra Technologies ------------------------------------------------------- The SF.Net email is sponsored by EclipseCon 2004 Premiere Conference on Open Tools Development and Integration See the breadth of Eclipse activity. February 3-5 in Anaheim, CA. http://www.eclipsecon.org/osdn _______________________________________________ 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:
- port number or'ing Craig Mueller (Jan 22)