Back to Tools | Summary | Entry Form | Teredo IPv6 Addresses

Summary Information

This page will convert an IPv4 address into it's default 6-to-4 equivalent, or vice versa. For 6-to-4, the IPv6 address is formed by using the IPv4 address and the following scheme:

IPv4: a.b.c.d translates to IPv6 2002:ab:cd::ab:cd

For IPv6, the octects are represented as a hexadecimal number, while IPv4 uses decimal. The 2002:/16 prefix is reserved for 6-to-4 addressing.

This page will also decode Teredo IPv6 addresses to extract the public IPv4 address of the host and the server. More special features and prefixes are being added.

IP Entry Form

Enter an IPv4 or IPv6 address:

This is experimental. please contact us about errors and improvements.

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How to Translate Teredo IPv6 addresses

  • First 32 bits: 2001:0000 (fixed Teredo prefix)
  • Second 32 bits: IPv4 address of the server
  • 16 Bits of Flags (determining what kind of NAT is in use)
  • 16 Bits for UDP port used (obfuscated)
  • last 32 Bits: public IPv4 address of the client

see RFC 4380 for details