Snort mailing list archives
[Snort-Devel] SNORT Detection-Plugin just call once
From: Emiliano Fausto <emiliano.fausto () gmail com>
Date: Wed, 12 Feb 2014 18:26:34 -0200
Hello there, I'm debugging with gdb a detection plugin I've developed, and there's something I am not fully understanding. I have this function (which should be called every time a packet matches one of my rules which invokes a keyword named "MyDP"): ... typedef struct _MyDPData { u_int16_t num; } MyDPData; ... int MyDPCheck(void *context, Packet *p) { LogMessage("My processing function was called\n"); MyDPData* mydata; if (!p->tcph) return DETECTION_OPTION_NOT_MATCH; mydata = (MyDPData *) context; if (mydata->num == 90) { LogMessage("it matched\n"); return DETECTION_OPTION_MATCH; } return DETECTION_OPTION_NOT_MATCH; } I'm facing 2 problems here: 1) When I'm debugging with GDB it seems that this function is being called just once. The moment it's called, is when the SNORT is parsing all the snort.conf file, and detects there's a keyword into a rule which matches: "MyDP". Then it doesn't matter how much packets validate the rest of the rule, it doesn't seems to be called (because the breakpoint over the function MyDPCheck isn't triggered any more). Note: It's strange, because my /var/log/snort/alert file is full of alerts referring to this alert being triggered, although I don't see the "it matched" message. My question is, shouldn't it be logging the message: "It matched?" each time it matches a packet calling this rule with the num==90? Snort.Conf rule -> alert tcp any any -> any any (MyDP: 90; msg: "My DP was called"; sid: 5016666; rev:1;) 2) I realized that it doesn't matter the number I put into the rule (in the previous example I just put 90), the Detection Plugin always returns "True" --> DETECTION_OPTION_MATCH. So, it doesn't make any sense to me, as it's a really simply comparison between the number stored option value and the hard-coded value 90. In this case, I'm almost sure that the alert should NOT be triggered if I put numbers different than 90 in the keyword value, right? Thanks in advance to anyone which could give me some light on this matter! Emiliano.
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Current thread:
- [Snort-Devel] SNORT Detection-Plugin just call once Emiliano Fausto (Feb 12)
- Re: [Snort-Devel] SNORT Detection-Plugin just call once John Eure (Feb 12)
- Re: [Snort-Devel] SNORT Detection-Plugin just call once Emiliano Fausto (Feb 13)
- Re: [Snort-Devel] SNORT Detection-Plugin just call once Emiliano Fausto (Feb 13)
- Re: [Snort-Devel] SNORT Detection-Plugin just call once John Eure (Feb 15)
- Re: [Snort-Devel] SNORT Detection-Plugin just call once Emiliano Fausto (Feb 17)
- Re: [Snort-Devel] SNORT Detection-Plugin just call once Emiliano Fausto (Feb 13)
- Re: [Snort-Devel] SNORT Detection-Plugin just call once John Eure (Feb 12)