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Re: preprocessor definition in snort manual!?!?!?
From: Matt Kettler <mkettler () evi-inc com>
Date: Mon, 21 Apr 2003 17:33:29 -0400
Really it should say programmers and users that are comfortable doing programming.
Essentially snort has a standard C code interface that allows for add-on modules that are written in C to be compiled into snort. These consist of preprocessors and plugins, both of which can examine packets, but only preprocessors actually data before the rules are applied.
A prime example of a snort preprocessor is stream4, which re-assembles the data out of multiple packets in a TCP stream. Another example is the code that normalizes out HTTP requests (I forget the name of this module), so that unicode and escape sequences in HTTP requests are decoded prior to being searched by rules (this prevents evasion of rules looking for things like "cmd.exe". Otherwise an attacker could just use escape codes to avoid matching).
If you're comfortable with C code, you can look in the src/preprocessors subdirectory for some examples of how a preprocessor is written.
At 11:23 PM 4/21/2003 +0300, Derya Sezen wrote:
Hi, What does this sentence in snort manual mean!? "Preprocessors allow the functionality of Snort to be extended by allowing users and programmers to drop modular "plugins" into Snort fairly easily." What kind of "plugins" that it mean? How can we use this function to make a plugind? Can you give an example to that?! -- Derya Sezen <funky () gsu linux org tr>
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Current thread:
- preprocessor definition in snort manual!?!?!? Derya Sezen (Apr 21)
- Re: preprocessor definition in snort manual!?!?!? Matt Kettler (Apr 21)