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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If you take a bit deep analyses on SIP packet you will be able to understand the issue,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Iptables filter on layer-3 while SIP is on layer-7. It is easily possible to generate a SIP packet with different source-ip than physical interface.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>You can also simulate it if you set external-ip=some-else-ip in SIP.com in asterisk. All you SIP packets will contain new some-else-ip while layer-3 headers will still have actual physical interface IP.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> asterisk-users-bounces@lists.digium.com [mailto:asterisk-users-bounces@lists.digium.com] <b>On Behalf Of </b>RSCL Mumbai<br><b>Sent:</b> Monday, August 08, 2011 5:18 PM<br><b>To:</b> Asterisk Users Mailing List - Non-Commercial Discussion<br><b>Subject:</b> Re: [asterisk-users] Firewall Issue<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p><div><p class=MsoNormal>On Mon, Aug 8, 2011 at 5:09 PM, Henrik <<a href="mailto:singler@common-hacking.org">singler@common-hacking.org</a>> wrote:<o:p></o:p></p><div><p class=MsoNormal>Also you can set allowguest=no in sip.conf, if you didn't do it already<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div></div></div><p class=MsoNormal style='margin-bottom:12.0pt'>I will check sip.conf, but logically, the packets should not be reaching Asterisk.<br>IP Tables should have blocked them.<br><br>Sans<br><br><o:p></o:p></p></div></body></html>