As trusted third parties are increasingly being asked to make policy decisions on behalf of the various entities participating in an application's operation, a need has developed for applications to be able to communicate their needs to the devices in the network that provide transport policy enforcement. Examples of these devices include firewalls, network address translators (both within and between address families), signature management for intrusion detection systems, and multimedia buffer management. These devices are a subset of what can be referred to as 'middleboxes.' This working group will focus its attention on communication with firewalls and network address translators (including translation between IPv6 and IPv4). Work will not preclude extensibility to other categories of middle box. Decomposing applications requiring policy decisions by removing application logic from the middle box and instead providing a generalized communications interface provides a number of benefits, including improved performance, lower software development and maintenance costs, improved ability to support traversal of packet filters by complex protocols, easier deployment of new applications, and the ability to consolidate management functions. For example, by moving stateful inspection of protocols such as H.323 and SIP out of firewalls, it is possible to improve performance and scalability and reduce development and costs. This working group will concern itself with an environment that consists of: - one or more middle boxes in the data path - an external requesting entity - a policy entity for consultation purposes when the requesting entity is untrusted. The requesting entity may be trusted or untrusted. In the case where it is trusted, the middle box will treat the request from the entity as authoritative. In the case where it is not trusted, the intermediate device will have to verify that it is authorized to complete the request. That authorization could come from a separate or a built in policy server. The primary focus of the working group will be the application of this architecture to communicating requests between applications and firewalls or NATs. This will not preclude other uses, and care will be taken to ensure that the protocol is extensible. The working group will evaluate existing IETF protocols for their applicability to this problem, using the framework and requirements documents developed during the working group's first phase as criteria for the evaluation. If a protocol is found to be suitable it will be used as the basis for the development of a middlebox communication protocol. In the unlikely case that one is not found to be suitable, the working group will undertake development of a new protocol. Discovery of middle boxes is out of scope. The deliverables will be o a document evaluating existing IETF protocols for their suitability o a document specifying a middlebox communication protocol or profile based on the results of the protocol evaluation. This working group will only deal with firewalls and network address translators. Ubiquitous deployment of midcom in all middleboxes could take many years. In the interim, a solution is needed that allows applications to operate in the presence of midcom-unaware middleboxes. To support this, the midcom group will develop or document a protocol or approach that allows clients to indirectly obtain address bindings from midcom- unaware middleboxes, through communications with server elements on the public side of the middlebox. The key goals for this effort are rapid delivery of a simple solution (since it is an interim solution), consistency with the midcom framework, and security. In particular, any proposed interim approaches will address (and document) the architectural and pragmatic concerns described in [UNSAF].