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<TITLE>nat test based on rfc1918 address in call-id field</TITLE>
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<P ALIGN=LEFT><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">Hi,</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN></P>
<P ALIGN=LEFT><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">I am thinking about having more NAT test on a sip</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT SIZE=2 FACE="Arial">packet</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">.</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT SIZE=2 FACE="Arial">Just want to find out if it is useful.</FONT></SPAN></P>
<P ALIGN=LEFT><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">I run into some situations that some</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT SIZE=2 FACE="Arial">‘</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">smart</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">’</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial"> UAs</FONT> <FONT SIZE=2 FACE="Arial">try to detect its external IP</FONT><FONT SIZE=2 FACE="Arial"> and put the external IP address into the sip packet.</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT SIZE=2 FACE="Arial">Depending on the</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT SIZE=2 FACE="Arial">network and</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT SIZE=2 FACE="Arial">NAT</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT SIZE=2 FACE="Arial">firewall</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial"> setup</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">, it may or may not</FONT> <FONT SIZE=2 FACE="Arial">set the</FONT><FONT SIZE=2 FACE="Arial"> right external IP and port</FONT><FONT SIZE=2 FACE="Arial"> i</FONT><FONT SIZE=2 FACE="Arial">n the packet</FONT><FONT SIZE=2 FACE="Arial">.</FONT><FONT SIZE=2 FACE="Arial"> If it is not, but pretend</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">s</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial"> to</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT SIZE=2 FACE="Arial">be</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT SIZE=2 FACE="Arial">on</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT SIZE=2 FACE="Arial">the public internet, then there</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT SIZE=2 FACE="Arial">is</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT SIZE=2 FACE="Arial">most likely</FONT> <FONT SIZE=2 FACE="Arial">a</FONT><FONT SIZE=2 FACE="Arial"> one-way voice or no voice issue.</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT SIZE=2 FACE="Arial">I</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">’</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">d like to be able to detect</FONT><FONT SIZE=2 FACE="Arial"> and force it to use</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial"> a</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial"> nat proxy.</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT SIZE=2 FACE="Arial">By checking these packets, I found that the only trace</FONT> <FONT SIZE=2 FACE="Arial">is the private IP a</FONT><FONT SIZE=2 FACE="Arial">ddress in the call</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">-id header field.</FONT><FONT SIZE=2 FACE="Arial"></FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT SIZE=2 FACE="Arial">It will be useful to check</FONT> <FONT SIZE=2 FACE="Arial">if a RFC1918 address is used in the call-id.</FONT> <FONT SIZE=2 FACE="Arial">I understand that it is not a thorough test for NAT, well, just like any other NAT test.</FONT></SPAN></P>
<P ALIGN=LEFT><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">Can someone please comment if it is</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT SIZE=2 FACE="Arial">a good test?</FONT></SPAN></P>
<P ALIGN=LEFT><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">Thanks,</FONT></SPAN></P>
<P ALIGN=LEFT><SPAN LANG="en-us"><FONT SIZE=2 FACE="Arial">Richard</FONT></SPAN></P>
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