Re: Snort Rule Creation

["Joel Esler (jesler)" <jesler () cisco com>]

Maybe something like:

alert tcp $SOURCEIP any -> ![destip1, destip2, destip3] any (msg:”Unauthorized TCP traffic initiated”; flags:S; 
sid:1000000; rev:1;)

?


--
Joel Esler | Talos: Manager | jesler () cisco com <mailto:jesler () cisco com>






> On Jan 31, 2017, at 5:33 PM, John G <drterdnugget () gmail com> wrote:
>
> Good Afternoon everyone,
>
> My name is John and I am starting out with creating Snort rules.  I have experience using Snort with IDS's such as 
> Sourcefire and Security Onion for incident response.  However, i don't have much experience creating custom rules.  
> Although i once created a rule during one of my security classes during my undergrad program lol  Anyway, i have been 
> reading documentation for how to understand/create rules from a variety of sources.  But I wanted to reach out to you 
> guys and see what information you can provide.
>
> I have a device that is communicating with about 8 other devices.  I would like to write a rule that alerts if it 
> detects any communication outside of those devices.
>
> Is it possible to list multiple ip addresses within a rule and maybe use an is not "!=" attribute.
>
> So something like: alert tcp != sourceip1  80 -> destip1, destip2, destip3, etc (msg:"Alert Message";)
>
> I would appreciate any assistance and will continue to do my own research and see if i can figure it out on my own :)
>
> Regards,
> John
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Please visit http://blog.snort.org for the latest news about Snort!

Visit the Snort.org to subscribe to the official Snort ruleset, make sure to stay up to date to catch the most <a 
href=" https://snort.org/downloads/#rule-downloads";>emerging threats</a>!