Network Working Group P.A. Mart Internet Draft Marconi Communications Document: draft-tiphon-foglamps-00.txt P. Sijben Category: Informational Lucent Technologies R.P. Swale BT June 2000 Firewall Control Requirements Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 [1]. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. 1. Abstract This draft describes a set of requirements for a protocol between application level entities, acting as proxies, and packet filtering devices that implement policies determined by the application. The packet filters apply header translation and police flow rates. These requirements are considered initially in the context of IP telephony but may be extended further. 2. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119 [2]. Mart, Sijben and Swale Expires December 2000 1 Internet-Draft Firewall Control Requirements May 2000 3. Introduction The requirements in this memo arise from work in the ETSI Tiphon project. The requirements were generated in a context that allows the use of both SIP[3]and H.323[4] environments and are not intended to reflect the specific requirements of any system. A more detailed set of background information for these requirements can be found in the document "Compilation of TIPHON contributions on the firewall problem"[5]. The problem to be solved by the protocol is the need to able to pass packets from one IP based network under the same administration (an Autonomous System, AS) to another, while imposing packet based flow control, as required by a session-based application (like IP telephony). It seems reasonable to assume that these Autonomous Systems protect their internal policies using firewalls. The application uses a session control protocol to communicate among its entities. This protocol is not terminated on the firewall device itself. Each application needing packets to flow between autonomous systems and hence the firewall should be able to request that flows be allowed or disallowed independently of other applications. There is an underlying assumption that the firewalls may offer Address Translation for media flows. 4. Architecture The architecture assumed for the rest of this paper is given below: . +-------------+ +-------------+ . | Firewall | | Firewall | . | Controller | | Controller | . |Application 1| |Application 2| . +-------------+ +-------------+ . \ / . \ / <--- Firewall Control . \ / Protocol . +-------------------+ ---> . ---> | | ---> Packet Flows | Firewall | Packet Flows <--- . <--- | | <--- . +-------------------+ AS 1 . AS 2 Mart, Sijben and Swale Expires November 2000 2 Internet-Draft Firewall Control Requirements May 2000 5. Requirements to be placed on the Firewall Multiple Services Multiple services need to be supported e.g. Voice over IP, Facsimile over IP, Multi-Media over IP. This requirement extends to services which control flows and are not yet designed. This requirement is intended to provide a general- purpose mechanism for Applications to use in traversing NAT like devices. QoS considerations The firewall may provide QoS transport facilities for the packet flows. For example setting of DS-bytes. QoS of Flows On receipt of a request to allow a flow with a particular flow specification the firewall shall indicate whether or not available resources allow the flow to be carried. QoS Flow Enforcement Where the firewall has indicated that available resources allow a flow to be carried the firewall will enforce the flow specification contained in the original request. QoS Flow Exceptions The action to be taken when the flow specification is breached shall be determined on a flow by flow basis. A default behaviour that has been previously set shall be used by the firewall unless the firewall controller specifies a particular behaviour. The default behaviour shall be not to permit a flow of packets. Address Translation capabilities The intended Address Translation behaviour is that IP addresses within the IP header information may be modified as required by the controller, but that addresses appearing elsewhere in packets are left unaltered. Mart, Sijben and Swale Expires November 2000 3 Internet-Draft Firewall Control Requirements May 2000 Application Signalling The firewall shall support the forwarding of signalling received on one, or more, appropriate destination address/port combinations to appropriate controllers, e.g. a session control entity. Examples of such signalling protocols could include SIP, H.323 and RSVP[6]. Flow Topology A particular flow may pass through one, two or more firewall devices connected in series. Address Translation is possible at any or all of the firewall devices. The firewall control devices may be, but need not be, different, for each firewall. Allow Multiple Controllers The firewall shall support multiple controllers. Each controller may be acting on behalf of one or more applications and no relationship between controllers may be assumed by the firewall. An address/port tuple may only be under the control of a single controller at any particular time Multiple Uni-cast The firewall shall support the duplication of packets conveyed in a particular flow such that each copy is sent to a different destination address. 6. Requirements to be placed on the Firewall Controller No assumption of Stand-alone implementation The firewall controller shall be capable of implementation on the same platform as other functional entities (e.g. a SIP proxy or H.323.Gatekeeper) Physical separation from Firewall The firewall controller and the firewall may be some distance apart or may be co-located. Proxy capability The firewall controller may act on behalf of other parties i.e. behave as a proxy device. Mart, Sijben and Swale Expires November 2000 4 Internet-Draft Firewall Control Requirements May 2000 Protocol performance The protocol must be designed to support time-constrained operation. This may include, amongst other things, the use of short messages and minimal messages per operation. The protocol must not assume 0 (zero) delay in communication paths. The protocol must be able to be used over low speed links. 7. Requirements to be placed on the Firewall Control Protocol Unsolicited messages The protocol needs to support unsolicited messages, for event reporting and alarms. Normal Operations The default behaviour shall be to not permit flows of packets. An operation is needed to permit a flow, with a given flow specification and address translation, across the firewall. It shall be possible to indicate whether packets should be carried or discarded when a given flow specification is exceeded. An operation is needed to stop a flow across the firewall. An operation is needed to modify the address translation of an existing permitted flow. 8. Security Considerations Security issues are covered in the following requirements: Authentication Peers using this protocol must be authenticated in order for message exchange to proceed. Automatic discovery mechanisms shall not be permitted other than between mutually authenticated peers. This in order to prevent hacking into the firewall by impersonating a controller. Mart, Sijben and Swale Expires November 2000 5 Internet-Draft Firewall Control Requirements May 2000 Encryption The protocol must permit the use of strong encryption to protect the privacy of requests and responses. The protocol must permit the use of strong encryption to ensure the trustworthiness of requests and responses to prevent unauthorised use. 9. References 1 Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. 2 Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997 3 SIP: Session Initiation Protocol, Request for Comments: 2543,M. Handley, H. Schulzrinne, E. Schooler, J. Rosenberg , IETF March 1999 4 "Visual telephone systems and equipment for local area networks which provide a non-guaranteed quality of service," Recommendation H.323 version 3, Telecommunication Standardization Sector of ITU, Geneva, Switzerland, 2000 5 ETSI Tiphon meeting 18, Ottawa, May 22-26, Temporary Document 18TD028r1. R. Swale, BT. See www.etsi.org/tiphon for open access to documents. 6 Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification. R. Braden, Ed., L. Zhang, S. Berson, S. Herzog, S. Jamin. IETF RFC 2205, September 1997. 10. Acknowledgments None Mart, Sijben and Swale Expires November 2000 6 Internet-Draft Firewall Control Requirements May 2000 11. Author's Addresses Philip Mart Marconi Communications Ltd. Edge Lane Liverpool United Kingdom Email: philip.mart@marconi.com Paul Sijben Lucent Technologies NV Huizen Netherlands Email: sijben@lucent.com Richard Swale BT Adastral Park Ipswich United Kingdom mail: richard.swale@bt.com Mart, Sijben and Swale Expires November 2000 7 Internet-Draft Firewall Control Requirements May 2000 Full Copyright Statement "Copyright (C) The Internet Society (date). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implmentation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into Mart, Sijben and Swale Expires November 2000 8