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<p class="MsoNormal">Hi OISF team,<o:p></o:p></p>
<p class="MsoNormal">We are trying to explore and add new content modifier fields for SMTP/DNS/ SMB protocols. Also we would like to expand this to other protocols based on our requirements.<o:p></o:p></p>
<p class="MsoNormal">At present, Suricata has a very good coverage for HTTP protocol.
<o:p></o:p></p>
<p class="MsoNormal"><a href="https://suricata.readthedocs.io/en/suricata-4.1.2/rules/http-keywords.html">https://suricata.readthedocs.io/en/suricata-4.1.2/rules/http-keywords.html</a><o:p></o:p></p>
<p class="MsoNormal">HTTP content modifiers gives us better control to write a new rule or to modify existing signatures.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We are planning to have similar modifiers for protocols like SMTP, DNS, SMB.
<o:p></o:p></p>
<p class="MsoNormal">For example: SMTP packet exchange/flow contains a bunch of fields like
<span lang="EN">mailfrom, rcptto, date, from, to, cc, reply_to, subject, x_originating_ip, user_agent et al.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN">Something like : alert smtp $EXTERNAL_NET any -> $HOME_NET
</span>(content<b><i>:"username@example.com"; mail_from</i></b>; sid:1;)<o:p></o:p></p>
<p class="MsoNormal">The similar requirements holds good for other set of protocols mentioned.<span lang="EN"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN">We are interested in knowing <o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="mso-list:Ignore">1.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]><span lang="EN">What is the right approach to go about adding or modifying the rules with new content modifiers?</span><o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="mso-list:Ignore">2.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]><span lang="EN">What is the placeholder in the code if we start adding these new modifiers in the rules?</span><o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="mso-list:Ignore">3.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]><span lang="EN">If code changes are needed to implement this functionality what is the correct approach to accommodate these changes in existing Suricata design?</span><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Regards,<o:p></o:p></p>
<p class="MsoNormal">Aditya <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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