All About IPv6
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This document summarizes key aspects of IPv6 including: - IPv6 was proposed in 1999 as a replacement for IPv32 and has 128-bit addressing compared to IPv4's 32-bit addressing. - IPv6 features much larger subnet spaces, automatic device discovery, and link-local and site-local addressing prefixes. - IPv6 addressing includes the link-local prefix fe80 for LAN communication and the public address space prefix 20::/8. - While IPv6 subnetting is supported, a /64 subnet is typically used even for point-to-point links between two devices. - IPv4 addresses can be tunneled over IPv6 networks through services like Hurricane Electric
All About IPv6
- 2. Background • Replacement for IPv4 • Proposed in 1999 • Still not significantly used
- 3. IPv4 vs. IPv6 • 32bit addressing VS 128bit addressing • 0.0.0.0 VS :: (or 0::0) • 127.0.0.1 VS ::1 • BIG subnet space (64bits) • Auto-discovery • Link-local + Site-local
- 4. fe80 BLAH • Link-local prefix – similar to 10./192.168./etc in IPv4 (but NOT the same) • (Actually is the same idea as 169.254/16 defined by RFC3330, as used by Microsoft) • Shared by all machines sharing a LAN segment (network link) • Commonly used in IPv6 Autodiscovery
- 5. 20:: • Public allocated address space is 20::/8 • The majority of the IPv6 address space is reserved by the IANA “for a rainy day”
- 6. IPv6 Subnetting • • • • • It’s there. It’s supported… But it’s not “supposed” to be used ISPs get a /32 subnet “End user sites” get a /48 subnet Smallest “allocation” is typically a /64 subnet • Although subnets *could* be more or less than 64-bits, the IETF recommends always subnetting exactly 64 bits (even for a point-to-point link between only 2 devices)
- 7. 6 to 4 Tunnels • Any IPv4 address can be tunneled into the IPv6 network • Hurricane Electric is probably the most popular tunnel broker • Anyone with an IPv4 user can set up a tunnel to fully access IPv6
- 8. IPv4 and IPv6 Co-Existence • Most modern OS-es allow for “dual stack” • IPv6 is preferred, and IPv4 used as fallback • Servers and clients both follow the same rules
- 9. Security Considerations • NAT blocks your internal network from the public Internet • IPv6 addressing is (hypothetically) publicly routable • NAT hides your internal network structure • IPv6 address could theoretically contain machine-specific identification
- 10. Security Considerations • At the end of the day a firewall will block the traffic • … And clever address assignment and subnetting will deal with the rest
- 11. That’s All Interesting, But…
- 12. Apache HTTP Server • Supports IPv6 since 2001 (and documented since 2002) • 1.3 Supported IPv6 too via an unofficial patch • Supports dual-stacking in VirtualHost directive • Don’t forget to Listen and NameVirtualHost too • That’s all there is to it
- 14. Thank You!
Editor's Notes
- #7: RFC4291 RFC3627-section4