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Lessons from IPv6 Evolution: Addressing Security and Efficiency

Explore the history, decisions, and challenges of IPv6 development since 1992. Understand its impact on internet security, DHCP, NAT, and more. Discover why IPv6 adoption faced hurdles and lessons learned.

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Lessons from IPv6 Evolution: Addressing Security and Efficiency

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  1. Steven M. Bellovin smb@cs.columbia.edu Lessons from IPv6

  2. History • Effort started in 1992-1993 • Original primary purpose: more IP addresses • Several competing proposals

  3. Context • Internet security starting to be noticed • Note: security ≠ cryptography! • No deployed autoconfiguration – DHCP dates to 1993 • No NAT; first RFC was 1994 • OSI vs TCP/IP wars • Routing table size an issue

  4. Basic Decisions • Do not change basic semantic model of IP; keep it simple • Slightly modified over time... • Support other things seen as necessary • Mobility • Renumbering • Multicast • Add security: IPsec • Do not change TCP

  5. What Happened • Near-stalemate in the IETF among different proposals • IPng area and directorate formed • Arguments over cryptography (vs. U.S. export laws) • Routing table size was seen as not a primary issue • Use CIDR and easy renumbering • Engineering took a lot longer than expected

  6. Second System Effect • Many features were added to IPv6 • Scoped addresses • Required changes to the socket API • Neighbor Discovery replaced ARP • Includes basic autoconfiguration • Flow labels (but usage wasn't specified) • Early decision on stateless autoconfiguration froze part of the address format

  7. The Claims for V6 • Bigger addresses • True, but doesn't attract end users • Autoconfiguration • We now have DHCP for client configuration • More secure • IPsec exists for IPv4, too

  8. Engineering is Hard • Some features were much more complex than people thought • Neighbor Discovery couldn't be secured with IPsec • Site-local addresses interacted poorly with the DNS • Finishing the design took a lot longer than expected • Renumbering is easier, but still not easy; there are too many addresses in configuration files, access control lists, etc. • Multihoming is still unsolved

  9. What Happened? • The opportunity attracted too many feature creatures • During that time, IPv4 didn't stop evolving • Many of the putative advantages of IPv6 became part of IPv4 • Tighter allocation controls by the RIRs helped • NATs solved a large part of the address space crunch

  10. The World Changed under IPv6 • Mobility hasn't been that important at the IP layer • Layer 2 mobility often works well: 802.11 access points, cell phones, etc • Firewalls and VPNs have eroded much of the application base for mobility • ISP-based multihoming has become increasingly important – and it was explicitly ignored in the IPv6 design

  11. What are the Lessons? • The devil is in the details – you generally don't know what will work, or how well it will work, until you've built it • Understand what the real issues are • IPv6 got big addresses right; it didn't understand multihoming and looked too much at mobility • Understand what will motivate users to adopt it • NAT made big addresses irrelevant for most end users

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