[#XECS-1517] Subscription requests from external clients need to be handled by the RLS

sipXecs

Subscription requests from external clients need to be handled by the RLS

Created: 2008-06-14 09:59 Updated: Friday 13:54

Component/s:

sipXrls

Affects Version/s:

3.11

Fix Version/s:

4.2

Original Estimate:

Unknown

Remaining Estimate:

Unknown

Time Spent:

Unknown

Issue Links:

Related

This issue related to:
	XECS-1606 No authorization for dialog event sub...

Description

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Problem: When an external client (i.e. a client from a different domain that is not registered with the sipXecs proxy) sends a subscribe for line state or other event packages to a SIP URL on our system (i.e. subscribe to 1234@our-domain.com), then that subscription request is sent to the internal phone that registered under that contact. The RLS server is not involved.

Such requests need to be handled by the RLS on behalf of the UA, because:
   - We want to be able to implement policy so that we can allow / deny such requests
   - We need scalability where such requests are handled centrally
   - This needs to also work with phones that can only handle one subscription at a time

Therefore, the proxy needs to intercept and route all such subscription requests to the RLS. The RLS then either already has a subscription for that contact and uses it to service the request, or creates a new subscription to the contact on the fly.

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Scott Lawrence - 2008-06-14 21:01

There is a policy question here:

Should this be allowed at all?

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Dale R. Worley - 2008-06-16 11:00

In order to enforce permission, we need to be able to configure the phones to only allow such subscriptions from the RLS.

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Martin Steinmann - 2008-06-16 19:41

With all the subscription transactions going throuvgh the RLS a possible policy is to deny them all. However, in general this is a highly desirable capability first enabled by SIP

Phone's are typically on local (non-routable) IP addresses. Therefore, wouldn't a request from an EXTERNAL client have to be made using the domain name and therefore that request would always be routed to the RLS? Dealing with the security aspects of internal subscription requests, therefore, would be a different issue and would most likely require support in the phone.

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Paul Mossman - 2008-11-14 13:54

I'm also skeptical about implementing this. The privacy issue will be solved with XECS-1606. For scalability one can instead use a Resource List offered from sipXrls. Polycoms can now handle more than one subscription at a time, but even so by using a Resource List via sipXrls one would not incur an extra subscription to the phone.