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<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am using Squid in an interception role with WCCP.<o:p></o:p></p>
<p class="MsoNormal">I am peeking at Step1 to read the SNI and determining whether to splice or bump.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">That interception/MITM appears to fail where remote certificates from origin servers have way too many dnsnames in the SAN field. <o:p></o:p></p>
<p class="MsoNormal">I have noticed this behavior with at least these 2 websites. In both the cases, my setup would be bumping the connections. (Obviously otherwise we won’t be having this problem with splicing.)<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><a href="https://www.pcmag.com/">https://www.pcmag.com/</a><o:p></o:p></p>
<p class="MsoNormal"><a href="https://www.extremetech.com/">https://www.extremetech.com/</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The RFC doesn’t set an upper bound on the number of dnsnames you can set in the SAN field.<o:p></o:p></p>
<p class="MsoNormal">If I splice these domains/URLs, browsers don’t complain either. So this seems local to Squid.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Points to note: <o:p></o:p></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]>Even though openssl s_client can connect/negotiate just fine, Squid doesn’t.<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]>This is the behavior that I gather from a packet capture.
<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1">
<![if !supportLists]><span style="mso-list:Ignore">a.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>My client (say a workstation XYZ) tried to connect to 103.243.13.183:443 (That is
<a href="https://www.extremetech.com">https://www.extremetech.com</a>) <o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1">
<![if !supportLists]><span style="mso-list:Ignore">b.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>WCCP ships packet to the proxy over GRE tunnel and a TCP connection with the proxy acting as the origin server is established.<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1">
<![if !supportLists]><span style="mso-list:Ignore">c.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>XYZ sends ClientHello to the proxy.<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1">
<![if !supportLists]><span style="mso-list:Ignore">d.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Squid starts conversing the origin server and sends a ClientHello.<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1">
<![if !supportLists]><span style="mso-list:Ignore">e.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Origin server replies with ServerHello, ServerKeyExchange, Certificate packets, Squid just waits endlessly.<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1">
<![if !supportLists]><span style="mso-list:Ignore">f.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>The client, XYZ, ends up sending a FIN packet after ClientHello, since Squid doesn’t revert back with a ServerHello.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I will have to file a bug ?<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">Sarfaraz<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoListParagraph"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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