9 Feb
2010
9 Feb
'10
3:51 p.m.
Hello,
I am testing a cellphone software that registers with an Asterisk server
through an outbound proxy (Kamailio+rtpproxy). I am capturing network
traffic using wireshark and i notice that the SIP Register message from
the cellphone has an extra byte in the Content-Length header, which
causes Kamailio to discard the message with the following error output :
- ERROR:core:parse_content_length: parse error near char [13][^M]
- ERROR:core:get_hdr_field: bad content_length header
Could it be that this byte was appended somewhere downstream(possibly at
the wireless router..) or can i be sure that the byte was added during
SIP Message construction by the cellphone software ?
Thanks in advance,
Vikram.
9 Feb
9 Feb
4:11 p.m.
El Martes, 9 de Febrero de 2010, Vikram Ragukumar escribió:
Could it be that this byte was appended somewhere
downstream(possibly at
the wireless router..) or can i be sure that the byte was added during
SIP Message construction by the cellphone software ?
You cannot know it by just inspecting the request.
You could be behind a fu***** SIP-ALG enabled router rewritting SIP requests
"to fix the NAT".
You can get more information here:
http://www.voip-info.org/wiki/view/Routers+SIP+ALG
To detect if you router has SIP-ALG enabled you can try various options:
1) Ensure you are not using STUN in your client so the request arriving to the
proxy should contain client private address in Via and Contact header.
2) Try an utility I coded which detects if a host is behind a SIP-ALG enabled
router:
http://dev.sipdoc.net/wiki/sip-stuff/SIP-ALG-Detector
--
Iñaki Baz Castillo <ibc(a)aliax.net>
8:15 p.m.
Iñaki,
Thank you for your response.
You could be behind a fu***** SIP-ALG enabled router
rewritting SIP requests
"to fix the NAT".
To detect if you router has SIP-ALG enabled you can try various options:
1) Ensure you are not using STUN in your client so the request arriving to the
proxy should contain client private address in Via and Contact header.
I have checked the Via and Contact headers and they do contain the
client private address. I am using an SMC7004VWBR wireless router thats
about 8 years old. I have checked all the router settings and do not see
any option to enable/disable SIP ALG, so i presume the router is not
capable of rewriting SIP headers.
I will try your program out as another method of confirmation of the
router's SIP ALG capability.
I have found that this anomaly (extra byte in Contact-Length
header)occurs only while sending to the proxy on a specific port(5060).
By changing the port on which the proxy listens(7160), the
Contact-length header field is ok.
Is there a list of routers out there that we know for sure that are not
SIP ALG capable ?
Once again, thanks for you suggestions.
Regards,
Vikram.
10 Feb
10 Feb
3:10 a.m.
Am 10.02.2010 02:15, schrieb Vikram Ragukumar:
Iñaki,
Thank you for your response.
This would indicate a SIP ALG.
Klaus
You could be behind a fu***** SIP-ALG enabled
router rewritting SIP
requests "to fix the NAT".
To detect if you router has SIP-ALG enabled you can try various options:
1) Ensure you are not using STUN in your client so the request
arriving to the proxy should contain client private address in Via and
Contact header.
I have checked the Via and Contact headers and they do contain the
client private address. I am using an SMC7004VWBR wireless router thats
about 8 years old. I have checked all the router settings and do not see
any option to enable/disable SIP ALG, so i presume the router is not
capable of rewriting SIP headers.
I will try your program out as another method of confirmation of the
router's SIP ALG capability.
I have found that this anomaly (extra byte in Contact-Length
header)occurs only while sending to the proxy on a specific port(5060).
By changing the port on which the proxy listens(7160), the
Contact-length header field is ok. Is there a list of routers out there that we know for
sure that are not
SIP ALG capable ?
Once again, thanks for you suggestions.
Regards,
Vikram.
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Users(a)lists.kamailio.org
http://lists.kamailio.org/cgi-bin/mailman/listinfo/users
http://lists.openser-project.org/cgi-bin/mailman/listinfo/users
11 Feb
11 Feb
1:52 p.m.
Hello,
Just following up. Here is a link to a screen capture from Wireshark
that shows the extra byte in the Content Length header field of the
Register message.
http://signalogic.com/images/SMC7004VWBR_UDP_payload_with_SIP_message_gets_…
We use an SMC7004VWBR router, but tech support at SMC said the router
does not support SIP. Has anybody else seen a router make such a mod to
a SIP message ?
Thanks and Regards,
Vikram.
Vikram Ragukumar wrote:
Iñaki,
Thank you for your response.
You could be behind a fu***** SIP-ALG enabled
router rewritting SIP
requests "to fix the NAT".
To detect if you router has SIP-ALG enabled you can try various options:
1) Ensure you are not using STUN in your client so the request
arriving to the proxy should contain client private address in Via and
Contact header.
I have checked the Via and Contact headers and they do contain the
client private address. I am using an SMC7004VWBR wireless router thats
about 8 years old. I have checked all the router settings and do not see
any option to enable/disable SIP ALG, so i presume the router is not
capable of rewriting SIP headers.
I will try your program out as another method of confirmation of the
router's SIP ALG capability.
I have found that this anomaly (extra byte in Contact-Length
header)occurs only while sending to the proxy on a specific port(5060).
By changing the port on which the proxy listens(7160), the
Contact-length header field is ok.
Is there a list of routers out there that we know for sure that are not
SIP ALG capable ?
Once again, thanks for you suggestions.
Regards,
Vikram.
_______________________________________________
Kamailio (OpenSER) - Users mailing list
Users(a)lists.kamailio.org
http://lists.kamailio.org/cgi-bin/mailman/listinfo/users
http://lists.openser-project.org/cgi-bin/mailman/listinfo/users
2:06 p.m.
El Jueves, 11 de Febrero de 2010, Vikram Ragukumar escribió:
Hello,
Just following up. Here is a link to a screen capture from Wireshark
that shows the extra byte in the Content Length header field of the
Register message.
http://signalogic.com/images/SMC7004VWBR_UDP_payload_with_SIP_message_gets_
modified.jpg
We use an SMC7004VWBR router, but tech support at SMC said the router
does not support SIP. Has anybody else seen a router make such a mod to
a SIP message ?
I don't know that router but have dealed with other SMC routers and they *do*
include SIP-ALG built-in, and the worst: it cannot be dissabled in any way!
Check at this page (the list of SIP-ALG routers):
http://www.voip-info.org/wiki/view/Routers+SIP+ALG
So, if I understand correctly the Content-Length has the form:
Content-Length: 0 0
???
--
Iñaki Baz Castillo <ibc(a)aliax.net>
2:27 p.m.
Iñaki-
El Jueves, 11 de Febrero de 2010, Vikram Ragukumar
escribió:
Yes we have seen that page, but it does not mention the SMC7004VWBR specifically. If it
did we could send it to SMC
tech support.
Hello,
Just following up. Here is a link to a screen capture from Wireshark
that shows the extra byte in the Content Length header field of the
Register message.
http://signalogic.com/images/SMC7004VWBR_UDP_payload_with_SIP_message_gets_
modified.jpg
We use an SMC7004VWBR router, but tech support at SMC said the router
does not support SIP. Has anybody else seen a router make such a mod to
a SIP message ?
I don't know that router but have dealed with other SMC routers and they *do*
include SIP-ALG built-in, and the worst: it cannot be dissabled in any way!
Check at this page (the list of SIP-ALG routers):
http://www.voip-info.org/wiki/view/Routers+SIP+ALG So, if I understand correctly the Content-Length has
the form:
Content-Length: 0 0
Yes. An extra zero (0x30).
-Jeff
5238
days inactive
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7 comments
4 participants
participants (4)
-
Iñaki Baz Castillo -
Jeff Brower -
Klaus Darilion -
Vikram Ragukumar