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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="font-family:Wingdings"><span style="mso-list:Ignore">Ø<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-family:"Lucida Sans",sans-serif">That is pretty consistent with Scott's comments then. Quite possibly some automated thingy/widget/bot/whatever at Facebook is issuing a request to a resource protected by that
SP. The Facebook thingy is getting back the redirect from the SP, and in trying to play the role of the browser-compliant HTTP user agent, it's corrupting the request somehow and issuing it to the IdP. That or something similar is probably what's going
on.<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="font-family:Wingdings"><span style="mso-list:Ignore">Ø<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-family:"Lucida Sans",sans-serif">As Scott says, the User Agent from the Apache log would be very interesting.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Lucida Sans",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Lucida Sans",sans-serif">I did get the sysadmins to adjust the access logging to include User-Agent, and it looks like you guys were on the right track:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Lucida Sans",sans-serif">Mozilla/5.0 (compatible; Facebot 1.0;
<a href="https://developers.facebook.com/docs/sharing/webmasters/crawler">https://developers.facebook.com/docs/sharing/webmasters/crawler</a>)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Lucida Sans",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Lucida Sans",sans-serif">Now that I know where it is coming from and why, are there any constraints I can put in place at the IdP to reject these requests, or should I make those restrictions at the web server?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Lucida Sans",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Lucida Sans",sans-serif">Josh<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Lucida Sans",sans-serif"><o:p> </o:p></span></p>
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