Teredo – Tunneling IPv6 through NATs
Date: 2003-10-31
Speaker: Quincy Wu
National Chiao Tung University
IPv4 -to -IPv6 Transition Strategy (RFC 2893)
Dual Stack
Reduce the cost invested in transition by running both IPv4/IPv6 protocols on the same machine .
Tunneling
Reduce the cost in wiring by re-using current IPv4 routing infrastructures as a virtual link.
Translation
Allow IPv6 realm to access the rich contents already developed on IPv4 applications
Tunnels of IPv6 over IPv4
Encapsulating the IPv6 packet in an IPv4 packet
Tunneling can be used by routers and hosts
Manually Configured Tunnel
6to4 Tunnel (RFC 3056)
6to4 Tunnel
IPv6 Tunneling Problem (1/2)
IPv6 Tunneling Problem (2/2)
Teredo Service
Allow hosts behind NAT to access IPv6 without modifying NAT. It contains three basic components:
Teredo Client
A node wants to gain access to the IPv6 Internet.
Teredo Server
helper to provide IPv6 connectivity to Teredo clients.
Teredo Relay
An IPv6 router that can receive traffic from IPv6 realm to Teredo clients and vice versa.
Teredo Operation Model
Teredo Client gets its Teredo IPv6 address from Teredo Server.
Use Teredo Relay as Relay router.
Teredo Address Encoding
Teredo Prefix: 32 bit Teredo service prefix.
3FFE:831F::/32
Teredo Server IPv4: IPv4 address of the Teredo server.
Flags: 16 bits that document type of address and NAT.
Bit pattern: C00000UG00000000
C=1 if NAT is cone.
UG should set to 00 .
Obscured Teredo Client External Port: mapped UDP port of the client
Obscured Teredo Client External IPv4: mapped IPv4 address of the client
Teredo Tunnel: To host behind NAT
Trial of Teredo in NCTU
Protocol Decoder in Ethereal
Conclusion
Many users get private IPv4 address from their service providers, such as WLAN and GPRS. These users are unable to create IPv6 tunnels.
Before all NAT devices can be upgraded to support IPv6, Teredo service is useful for ISPs to provide IPv6 access to their users behind NAT.
Categories: News