From: "Dan Wing" <[EMAIL PROTECTED]>

   If those URIs included ";user=phone", there is a transitive 
   relationship between the SIP URI and the TEL URI.  Without
   ";user=phone", I agree that no meaning is supposed to be applied 
   to the user-part (the part to the left of the "@").

True.  In that case, we have SIP URIs which are essentially aliases
for tel URIs.  But in that case, any signing should be of the
fundamental tel URI, which then obviates the problem with an SBC that
translates one alias-URI into another.

   In SIP, you accomplish something similar to the TCP SYN cookie by
   sending a SIP request towards the E.164, asking them to sign the 
   request and return it to you.  Details are in 
   draft-wing-sip-e164-rrc-01.txt and comments are welcome.

It seems like this mechanism is at most as certain as the E.164
mapping that it uses for the "reverse direction".  I gather from the
Enum people there is some trouble with that.

It seems to me that in practice, people don't validate requestors by
checking their apparent IP address, but rather by whether they can
present certificates.  But that is probably an issue that has been
hashed over before...

Dale
_______________________________________________
Sip mailing list  https://www.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [EMAIL PROTECTED] for questions on current sip
Use [EMAIL PROTECTED] for new developments on the application of sip

Reply via email to