Snort mailing list archives
Re: Doubts creating rules
From: Joe McAlerney <joey () SiliconDefense com>
Date: Mon, 29 Oct 2001 11:30:46 -0800
Hello Federico, Federico wrote:
I've two "logical" problem, help me to solve it. 1) first doubt: I've a net: 192.168.1.0/24From this net, the 192.168.1.10, 192.168.1.40 and 192.168.1.50 can connectto 192.168.5.1 only with log, the others component of 192.168.1.0/24 must generate an alert... wich rule I must create?
var EXCLUDED_HOSTS [192.168.1.10/32,192.168.1.40/32,192.168.1.50/32] log tcp $EXCLUDED_HOSTS any -> 192.168.5.1 any (msg: "connection attempted"; flags:S;) This one will alert on all connection attempts from any address that is not $EXCLUDED_HOSTS. Unfortunately, this includes addresses outside the 192.168.1.0/24 range as well. I couldn't think of a way to specify 192.168.1.0/24 minus $EXCLUDED_HOSTS. Maybe someone else can chime in. alert tcp !$EXCLUDED_HOSTS any -> 192.168.5.1 any (msg: "connection attempted"; flags:S;)
2) Second Doubt (Established Connections) I protect my host with snort, so I've done this rule alert tcp HOST-B any -> HOST-A any (msg: "connection attempted";) when HOST-A connect to HOST-B:139 for netbios share, the HOST-B response the connection for establishing it, and snort generate an alert from it... I need only snort to log HOST-B attemp to HOST-A not, just established connection and data transfer. How to solve this problem ?
Specify that you only wish to look for SYN packets, which indicate the beginning of a TCP connection: alert tcp HOST-B any -> HOST-A any (msg: "connection attempted"; flags:S;) Hope this helps, -Joe M. -- | Joe McAlerney joey () silicondefense com | | Silicon Defense - Technical Support for Snort | | http://www.silicondefense.com/ | +-- --+ _______________________________________________ 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:
- Doubts creating rules Federico (Oct 29)
- Re: Doubts creating rules Joe McAlerney (Oct 29)