Tunnel Ingress Tunnel EgressIPv4 Network192.0.2.1 192.0.2.2

Src: 192.0.2.1

Dst: 192.0.2.2

Proto: 41

IPv4 Header

V6 Header

V6 Header V6 Header

20 02 c0 00 02 01

IPv4 address

6to4 IPv6 /48 prefix

192 . 0 . 2 . 1

16 32 48

IPv4 NetworkIPv4 Network

6to4 Site

6to4 Site

6to4 Site

6to4 Site

6to4 Site

6to4 Site

6to4 tunnels

2001 0000 c000 0201 48a3 ec77 5edc

IPv4 Teredo Server address

Teredo /128 address

192 . 0 . 2 . 1

16 32 64

IPv4 Teredo Client NAT Flag xntl UDP Port xtnl IPv4 address

10 . 1 . 2 . 3

80 96

50001 (Cone)

XORffff

XORffff

randompadding

Teredo Client

IPv4 NetworkIPv6 Network

RestrictedNAT

TEREDOSERVER

TEREDORELAY

IPv6 host

1

2

3

4

5

6

7

8

9

1. Teredo ICMPv6 Echo Request from Teredo Client to Server2. Forwarded IMCPv6 Echo Request from Server to Host3. IMCPv6 Echo Reply from Host to Relay4. Teredo bubble from Relay to Server5. Teredo bubble from Server to Client6. Teredo bubble from Client to Relay7. Forwarded Teredo ICMPv6 Echo Reply from Relay to Client8. Initial packet Teredo-tunnelled from Client to Relay9. Forwarded initial packet from Relay to host