home_net and external_net: how to use ! with multiple subnets ?

[Tom Van Overbeke <tvanoverbeke () ccncsi net>]

Hi,


We have installed snort on our firewall, listening on the external
interface.

on the internal side, we have various lan's / dmz's etc, the external ip
interface (public ip adress) is connected to a hub, on which another public
ip adress (that i also want to consider as 'home_net' is connected.

Now i'd like to consider external net as 'everything that is not home_net',
but i can't get the syntax right. so for the moment i have only excluded our
main lan in external net.
the problem being that alot of false alerts are logged that come from the
other local subnets.

this is my current definition:

var HOME_NET
[172.21.0.0/16,172.16.208.0/27,172.16.208.32/27,195.xxx.xxx.xxx/32,195.xxx.x
xx.xxx/32]
var EXTERNAL_NET !172.21.0.0/16



is there a way to define external_net as 'everything that is not home_net',
and if yes, what's the correct syntax ?
if this is not possible, is it possible in the rules to replace  the
external_net -> home_net by specific subnets ?


thx,


Tom.


****************************************************************************
Disclaimer: 
This electronic transmission and any files attached to it are strictly 
confidential and intended solely for the addressee. If you are not 
the intended addressee, you must not disclose, copy or take any
action in reliance of this transmission. If you have received this 
transmission in error, please notify the sender by return and delete
the transmission.  Although the sender endeavors to maintain a
computer virus free network, the sender does not warrant that this
transmission is virus-free and will not be liable for any damages 
resulting from any virus transmitted. 
Thank You.
****************************************************************************



-------------------------------------------------------
This SF.net email is sponsored by Dice.com.
Did you know that Dice has over 25,000 tech jobs available today? From
careers in IT to Engineering to Tech Sales, Dice has tech jobs from the
best hiring companies. http://www.dice.com/index.epl?rel_code=104
_______________________________________________
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