Wayne,
Thanks for your reply.
By the way, I have got one more question regarding your replay.
The scenario I have mentioned is only possible with a help of the stateful
proxy. That was what you explained, wasn't it ?
Supposing that all the users are just UAs, then no one - except the two
parties involved the transaction - can cancel the transaction of other
parties because no one knows Call-Id, CSeq, etc.
The changed scenario is;
User A User B User C
Stateful Proxy
----------INVITE----------->
<--------100/180------------
* <--------CANCEL (A<->B) : IMPOSSIBLE! ------ *
<---------CANCEL : POSSIBLE-------------------------------------------
Regards,
Jun
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Wednesday, May 25, 2005 4:10 PM
To: Hyoungjoon Park
Cc: [email protected];
[EMAIL PROTECTED]
Subject: Re: [Sip-implementors] Canceling INVITE transcation by other party
Jun,
Please see response inline.
Hi,
I wonder if a user's INVITE transaction can be cancelled by other user. The
scenario is as follows;
User A User B User C
----------INVITE----------->
<--------100/180------------
<----------To cancel the transaction----------
----------CANCEL---------->
<--------200 OK-------------
The Question is that whether the user C is able to cancel the transaction
between the user A and B.
Wayne: I think it is possible but it is wrong for another user to do it, l
ike a MITM attack. But CANCEL is hop by hop so a stateful proxy may CANCEL a
request which is legit.
What kind of method can be used ? Would it be a REFER with method=cancel or
just CANCEL ?
Wayne: Just CANCEL
By the way, I'm really wondering if the scenario makes sense actually.
Wayne: The question makes sense, I am in doubt on the scenario though.
Regards,
Jun
Regards - Wayne
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