Snort mailing list archives
[Fwd: Re: Re: I don't get any alerts when reading from file.]
From: <dimopoulos () mhl tuc gr>
Date: Tue, 3 Aug 2004 12:34:42 +0300 (EEST)
First of all, thanks for your time! Now, here is the entire process I use. I have written a small program in C++ that reads all the .rules files that have a 'content' field and generates fake IP packets that match those rules. The packets contain all the necessary header data (IP and TCP/UDP) to match the rule along with the necessary payload (random but with content that matches that of the rule). I write these packets in hexdump format and then use the tool 'text2pcap' of Ethereal to convert it from hexdump to tcpdump format,using teh command line "text2pcap -q -l 12 <source> <destination>", and after that I take the newly generated file and feed it to snort. Using the -vd switches I can see that the IP addresses, ports and payload are ok (i.e. should match) yet I get nothing. And the fake samples I use are large enough (250000 packets) that at least some should have triggered. I tried running snort like snort -c snort.conf -A console -b -r test.txt but nothing changed. PS: I used snort to log some packets off the net and then fed the snort-generated log file to snort. Those logs DID trigger snort. Could the problem be with Ethereal? Or am I simply banging my head against a wall?Thanks!
How did you create the tcpdump file? What was the command line you used with tcpdump? Can you try running Snort like this: snort -c snort.conf -A console -b -r test.txt What makes you think that every packet should be generating an alert? Which SID do you expect to be firing? You might want to start with a simpler test to just detect the specific alert that you're looking for. You could even write a custom rule for it... -Marty -- Martin Roesch - Founder/CTO, Sourcefire Inc. - (410)290-1616 Sourcefire: Intelligent Security Monitoring roesch () sourcefire com - http://www.sourcefire.com Snort: Open Source Network IDS - http://www.snort.org
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Current thread:
- [Fwd: Re: Re: I don't get any alerts when reading from file.] dimopoulos (Aug 03)
- Re: [Fwd: Re: Re: I don't get any alerts when reading from file.] Martin Roesch (Aug 03)