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.

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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

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