Re: [Sip] SIP Dialog Match

["T Satyanarayana-A12694" <satyanarayana.t at motorola.com>]

Well, strictly speaking, this is possible and most SIP networks are
vulnerable to this. This is no different from HTTP or SMTP where this is
possible.

The guidelines (there could be others as well) to overcome this are:

1. Implement a known-good-source kind of logic where you accept
responses coming only from a well known proxy. Ofcourse, this works only
when there is a proxy and when the source IP address of the response
itself is not modified.

2. Implement encryption (e.g. TLS) for signaling

Regards
Satya T

-----Original Message-----
From: sip-bounces at ietf.org [mailto:sip-bounces at ietf.org] On Behalf Of
Karunesh Sharma
Sent: Friday, August 07, 2009 6:37 PM
To: Dale Worley
Cc: sip at ietf.org
Subject: Re: [Sip] SIP Dialog Match

Dale:

It's simple scenario where 'A' sent INVITE to 'B'. 'C' is man in middle
captured the INVITE and sent the response back to 'A'. I wonder why no
one ever had such case ever and why there is no established guidelines.

K$
_______________________

-----Original Message-----
From: Dale Worley [mailto:dworley at nortel.com]
Sent: Monday, August 03, 2009 9:35 PM
To: Karunesh Sharma
Cc: aayush bhatnagar; sip at ietf.org
Subject: RE: [Sip] SIP Dialog Match

On Mon, 2009-08-03 at 21:28 +0530, Karunesh Sharma wrote:
> Is this a valid behavior for scenario like 'Call-Forwarding'?

In principle, the responses to a request should almost always come from
the address to which the request was sent.  But that is not usually
enforced, and there may be good reasons why it isn't happening in a
particular instance.

In regard to an observed instance of this behavior, you must first
determine the complete routing of the request in question and the reason
for each routing step.

Dale


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