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<title>Multiple networks source address</title>
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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Even if you come up with a mechanism to
change the Source address it does not solve the problem completely.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>The reason is “The IP address in the
<st1:Street w:st="on"><st1:address w:st="on">Record Route</st1:address></st1:Street>
also needs to be changed(manipulated) so that Subsequent Requests for the same
call  coming from the other end of the Tunnel are routed correctly.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Kasturi<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> T.R. Missner
[mailto:trmissner@bandwidth.com] <br>
<b><span style='font-weight:bold'>Sent:</span></b> Tuesday, January 02, 2007
11:12 AM<br>
<b><span style='font-weight:bold'>To:</span></b> devel@openser.org;
users@openser.org<br>
<b><span style='font-weight:bold'>Subject:</span></b> [Users] Multiple networks
source address</span></font><o:p></o:p></p>
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12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Verdana><span style='font-size:9.0pt;
font-family:Verdana'>Hello,<br>
<br>
I ran into a seemingly strange issue using openser to proxy an invite from the
public internet to a private ipsec tunnel on my network.<br>
<br>
The problem appears to be caused by the fact that the packet is sent out to on
the correct interface ( eth1 in my case ) but still is using the source address
of et0 in the ip header. This is causing my ipsec tunnel to ignore the packet.<br>
<br>
Is there anyway to control the source addr in the IP header?<br>
<br>
Using a simple python script to send a upd packet across the same path I have
verified this is not a tunnel issue.<br>
<br>
Example<br>
et0: 4.X.X.229 packet arrives on this interface<br>
eth1: 10.X.X.13 packet is sent out this interface<br>
<br>
RURI is re-written and t_relay is used to send the packet to <br>
destination: 10.X.X.115<br>
<br>
Here is a partially redacted packet as captured by tethereal:<br>
<br>
Frame 1 (982 bytes on wire, 982 bytes captured)<br>
Arrival Time: Jan 2, 2007 16:49:35.536412000<br>
[Time delta from previous packet: 0.000000000 seconds]<br>
[Time since reference or first frame: 0.000000000
seconds]<br>
Frame Number: 1<br>
Packet Length: 982 bytes<br>
Capture Length: 982 bytes<br>
[Frame is marked: False]<br>
[Protocols in frame: eth:ip:udp:sip:sdp]<br>
Ethernet II, Src: DellComp_f6:27:19 (00:06:5b:f6:27:19), Dst: DellComp_ec:8d:a3
(00:06:5b:ec:8d:a3)<br>
Destination: DellComp_ec:8d:a3 (00:06:5b:ec:8d:a3)<br>
Address: DellComp_ec:8d:a3
(00:06:5b:ec:8d:a3)<br>
.... ...0 .... .... .... .... =
IG bit: Individual address (unicast)<br>
.... ..0. .... .... .... .... =
LG bit: Globally unique address (factory default)<br>
Source: DellComp_f6:27:19 (00:06:5b:f6:27:19)<br>
Address: DellComp_f6:27:19 (00:06:5b:f6:27:19)<br>
.... ...0 .... .... .... .... =
IG bit: Individual address (unicast)<br>
.... ..0. .... .... .... .... =
LG bit: Globally unique address (factory default)<br>
Type: IP (0x0800)<br>
<b><font color=red><span style='color:red;font-weight:bold'>Internet Protocol,
Src: 4.X.X.229 (4.X.X.229), Dst: 10.X.X.108 (10.X.X.108) ------>
should source from 10.X.X.13 not 4.X.X.229<br>
</span></font></b> Version: 4<br>
Header length: 20 bytes<br>
Differentiated Services Field: 0x10 (DSCP 0x04: Unknown
DSCP; ECN: 0x00)<br>
0001 00.. = Differentiated
Services Codepoint: Unknown (0x04)<br>
.... ..0. = ECN-Capable
Transport (ECT): 0<br>
.... ...0 = ECN-CE: 0<br>
Total Length: 968<br>
Identification: 0x0076 (118)<br>
Flags: 0x04 (Don't Fragment)<br>
0... = Reserved bit: Not set<br>
.1.. = Don't fragment: Set<br>
..0. = More fragments: Not set<br>
Fragment offset: 0<br>
Time to live: 64<br>
Protocol: UDP (0x11)<br>
Header checksum: 0x1dfe [correct]<br>
[Good: True]<br>
[Bad : False]<br>
Source: 4.X.X.229 (4.X.X.229)<br>
Destination: 10.X.X.108 (10.X.X.108)<br>
User Datagram Protocol, <st1:PlaceName w:st="on">Src</st1:PlaceName> <st1:PlaceType
w:st="on">Port</st1:PlaceType>: 5060 (5060), <st1:place w:st="on"><st1:PlaceName
w:st="on">Dst</st1:PlaceName> <st1:PlaceType w:st="on">Port</st1:PlaceType></st1:place>:
6060 (6060)<br>
Source port: 5060 (5060)<br>
Destination port: 6060 (6060)<br>
Length: 948<br>
Checksum: 0x1c67 [incorrect, should be 0x222a]<br>
Session Initiation Protocol<br>
Request-Line: INVITE sip:+1720560XXXX@10.X.X.108:6060
SIP/2.0<br>
Method: INVITE<br>
[Resent Packet: False]<br>
Message Header<br>
Record-Route:
<sip:4.X.X.229;lr;ftag=as0473b81f><br>
Via: SIP/2.0/UDP
4.X.X.229;branch=z9hG4bK7a42.e0b9bac5.0<br>
Transport:
UDP<br>
Sent-by
Address: 4.X.X.229<br>
<br>
<br>
<br>
.....<br>
<br>
<br>
Any clues on how to fix this problem?<br>
<br>
Thanks,<br>
<br>
T.R.</span></font><o:p></o:p></p>
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