[Kamailio-Users] Extra byte in Content-length header

Vikram Ragukumar vragukumar at signalogic.com
Wed Feb 10 02:15:31 CET 2010


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.



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