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NFCC Packet Filter Control Protocol. NFCC Control Protocol Characteristics. NFCC requires a control protocol for clients to dynamically update policy. Must fulfill NFCC functional requirements. Must be efficient (traverses air interface).
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NFCC Control Protocol Characteristics • NFCC requires a control protocol for clients to dynamically update policy. • Must fulfill NFCC functional requirements. • Must be efficient (traverses air interface). • Must present an appropriate security model for NFCC use cases. • Should be light enough to easily implement on mobile nodes.
NSIS NAT/FW NSLP • The NSIS NAT/FW NSLP was designed for path coupled configuration of NAT and packet filtering devices. • NSLP is a candidate for the NFCC control protocol. • NSLP has some potential risks in the context of NFCC.
NSLP Risks • Does path coupled signaling work? • Asymmetric routing? • When nothing is transmitted (open a passive socket use case)? • Is a soft state model best? • Cost of state refreshing? • Vulnerabilities introduced by obsolete state? • No defined filtering model. • Implied model is filtering only on single source and destination addresses and ports.
NSLP Risks (Continued) • No transactional semantics. • Atomic creation/deletion of sets of rules is important to avoid unintentional vulnerabilities. • Complex trust model. • All NSLP middleboxes must be able to decrypt and rewrite control messages. • Incomplete security model. • Firewall session authentication and authorization not yet defined. • No end to end security by design.
NSLP Risks (Continued) • NSLP is currently incomplete. • Complete is time for NFCC? • Will it support all of NFCC requirements (don’t let the tail wag the dog)? • Will such a novel and complex protocol work? • NSLP currently looks to be relatively complex (and expensive) to implement.
PFCP • PFCP (Packet Filter Control Protocol) is an alternative to NSLP. • Designed, ground up, for NFCC requirements. • Light-weight and efficient on the air interface. • Client-server rather than path coupled. • Hard state rather than soft state. • Simple trust model and complete security model. • Security from existing standards (TLS or IPSec). • Complete specification available.
Why Client-Server? • Client-server works as well as path coupling. • Automated server discovery (DNS, DHCP). • Server knows network topology and updates filters as required. • Server can act as client to servers in adjacent networks.
Client Server is Better • Client–server is better than path coupling. • Works with asymmetric routing. • Works with NFCC use cases such as passive sockets. • Packet filtering technology doesn’t need to be NFCC enabled. • Leverage existing security protocols. • Simpler to specify and implement.
Conclusion • 3GPP2 needs to evaluate the technical risks associated with adopted the NAT/FW NSLP for NFCC. • PFCP is provided as a specific alternative control protocol for consideration.