Subash RFC3261 says that generally, the CANCEL will be accepted by a server as long as it comes from the same previous hop as the original request. It does not state that CANCEL SHOULD or MUST be sent without credentials.
By previous hop, I assume the reference is to the VIA header, right? Since this can be easily spoofed, it is not very secure. Anyway, my question was that if the CANCEL originated at a UAC (not a proxy), it can be sent with credentials. In this case, the credentials can be validated. In a proxyless network(!), this technique can be used, instead of the previous hop validation using the VIA header. In such a case, should the nc-value be incremented? I think the answer is yes. Venkat -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] Sent: Wednesday, January 08, 2003 9:58 PM To: Arunachalam Venkatraman Cc: [EMAIL PROTECTED] Subject: Re: [Sip-implementors] Credentials in CANCEL - qop nc-value Hi Venkat, The CANCEL request is never challenged by any element since it cannot be resubmitted. Therefore you need not compute and add credentials in this request. The CANCEL will be accepted by any server as long as it comes from the same previous hop as the original request. Subhash Nayak Hughes Software Systems http://www.hssworld.com "Arunachalam Venkatraman" <[EMAIL PROTECTED]> on 01/09/2003 06:34:44 AM To: [EMAIL PROTECTED] cc: (bcc: Subhash Ullal Nayak/HSSBLR) Subject: [Sip-implementors] Credentials in CANCEL - qop nc-value The UAC behavior for CANCEL is not discussed in RFC 3261. When a UAC computes the request digest for CANCEL, should it use the nc-value unchanged from the INVITE or should it increment the nc-value? In general, every request should have a new nc-value (except ACK, of course), so I think this will apply to CANCEL. Is this correct? Venkat _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
