<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 14 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Hi,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I want to add the capability for Suricata to check various fields in the content of a DNS packet such as invalid query class, invlaid query type, invalid response class, invlaid response type, time-to-live of cached RR below a certain threshold, invalid label character, …<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>It seems the right way to do this may be to add an application layer module. Would you agree?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I couldn’t find documentation about application layer modules on the web site. Is there any available?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>It appears an application layer module is triggered by packet content. I got this impression by looking at calls to AplProtoAdd. Is this correct? Is there a way to trigger an application layer module based on port?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks,<o:p></o:p></p><p class=MsoNormal>Carl Soeder<o:p></o:p></p></div></body></html>