Subject: [SIP] Via header encryption and "received" parameter.

From: Nilesh Trivedi <[email-masked]>
Date: Thu, 03 Aug 2000 16:16:22 -0400

Hello all,

  Good afternoon.

  Has there been any thoughts on what should be done in case of "Hide"
  header is present and the previous hop Via has been received from a
  different network address, in case of which the proxy will append a
  'received' parameter to the topmost received Via.

  Hiding is performed only on the "host" and "port" but the received
  parameter is still forwarded un-encrypted, so we are exposing route
  information here.

  Thanks for your time and inputs. Have a very good day!!

Regards,

Nilesh Trivedi.

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From: Jonathan Rosenberg <[email-masked]>
Date: Fri, 04 Aug 2000 00:07:26 -0400

This already came up on the list and we agreed it should be hidden also.
In fact, this has already been folded into rfc2543bis. Quoting section
6.26:

> A server hides the previous hop by encrypting the “host” (in both sent-by and via-received), “port”,
> “maddr” parts of the top-most Via header field with an algorithm of its choice. Servers SHOULD add
> additional “salt” to the “host”and“port” information prior to encryption to prevent malicious downstream
> proxies from guessing earlier parts of the path based on seeing identical encrypted Via headers. Hidden Via
> fields are marked with the “hidden” Via option, as described in Section 6.47.

-Jonathan R.

-- 
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