Subject: Received Header

From: [email-masked]
Date: Tue, 2 Nov 1999 19:00:18 +0530

Hi, the sip RFC states that an proxy should
check for Via and compare it with the IP address of the receiving datagram
- if they are not equal, a received= must be added.

Now, when a response to this message is to be given, should it be given to
the received address or the Via address ?
It seems logical that it should be received, and is useful for NAT
complications,
but it imposes a problem if say a particular environment has many SIP
applications using a single SIP Stack running independantly on a node -
which may well be the case for limited resource environments.
In this case, the receiving proxy will see that Via shows one IP (of
client) but actual IP address of datagram is that of Stack node and add a
received line with IP of stack node.

Just wanted to know if this means that if receivng proxys will send it to
"received" instead of "Via" then an additonal burden of trying to spoof IP
address at stack node need to be perfirmed (to match that of client node)

Is the understanding of the received header and its implications correct in
the above text or are we thinking too much ?

Regds
Arjun

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From: Jonathan Rosenberg <[email-masked]>
Date: Wed, 03 Nov 1999 00:05:55 -0500

> the received address or the Via address ?

Received address. Otherwise, why bother recording it in the via header?

> received line with IP of stack node.

Thats fine. On your "stack node", each instance can use a different
port. The received tag applies only to the IP address; the port is still
whatever is in the Via header itself (5060 if not specified).

> address at stack node need to be perfirmed (to match that of client node)

I don't understand what you mean by spoofing the IP address of the stack
node. Who is spoofing what address, and why?

-Jonathan R.
-- 
Jonathan D. Rosenberg                       200 Executive Drive
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