[Snort-users] Alert on web traffic instead of IP Address?

Frank Knobbe frank at ...9761...
Fri Aug 14 15:49:13 EDT 2009

On Tue, 2009-08-11 at 10:32 -0400, Isherwood, Jeffrey - AES wrote:
> However I would like to create a few rules that look for traffic
> headed to a website that might be using Dynamic DNS (or fast flux) and
> so I do not know the IP Address of the dst host.
> For the IP Address alerts I use the following rule:
> Where $HOME_NET is my internal network and $MALICIOUS_IP is the IP
> Address of a site that we have deemed to be dangerous.  I don’t think
> that I can put a website name in the variables… and with Dynamic DNS
> and FastFlux changing the IPs I can’t figure out how to alert on
> malicious sites being hidden behind the changing IP addresses.

If you are trying to catch regular, unencrypted web traffic, match on a
specific Host Header in the GET|POST|HEAD|whatever request.

content:"|0d 0a|Host|3a 32|www.evilsite.com|0d 0a|";


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