IPv6 Address Calculator

The forms below give you the ability to calculate various properties of IP addresses and the texts around them give you some hints about how to use them.

IPv4 Addresses

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Misc Address	/
Network Mask
Network Base	192.168.0.0
First usable Address	192.168.0.1
Last usable Address	192.168.0.253
Default Gateway	192.168.0.254
Broadcast Address	192.168.0.255

The following special addresses and networks exist in IPv4:

0.0.0.0 the "ANY" address that is used by programs to speak to all network interfaces, it is never used directly. The whole network 0.*.*.* is reserved for special purposes (like DHCP).

10.*.*.*
172.16.*.* - 172.31.*.*
192.168.*.* are private addresses - you can use them freely within your own LAN. They will not be routed in the Internet.

127.0.0.1 is the localhost address, used by each host to talk to itself, there is always a special loopback interface preconfigured with this address, you never assign it to a real network device. The entire 127.*.*.* network is reserved for (host-)local networking.

169.254.*.* Link-Local addresses. These are automatically generated by some operating systems and (e.g. MacOS and Linux with Avahi installed) and are only usable for local communication in the LAN segment.

198.18.*.* - 198.19.*.* Network benchmark tests, this should never be used in production networks.

198.51.100.*
203.0.113.* TEST-NET-2, Documentation and examples
TEST-NET-3, Documentation and examples

224.*.*.* Multicasts (former Class D network) - Warning: the data shown when you click this network is not completely accurate - e.g. there is no default gateway or broadcast for multicasting

240.0.0.0/4 Reserved (former Class E network)

255.255.255.255 Link Broadcast - this is sent to all hosts on the same network link, but does not cross routers

IPv4 to IPv6 Transitional

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IPv4 in IPv6 Addresses

In some configurations IPv4 addresses can be written or used in IPv6 notation or they become part of an IPv6 address. This form allows you to convert from IPv4 to IPv6 and back. Depending on your application you may have to shift the IPv6 segments.

IPv4 Address: Please use dotted decimal notation.

IPv6 Address: Please use hexadecimal notation with the relevant 32 bits to the far right.

6to4 and 6RD Network Prefix

6to4 and 6rd are transitional mechanisms that will be used until native IPv6 is universally available. With both mechanisms you can assign an IPv6 prefix to an entire network based on the IPv4 address of the gateway. Both use the 6in4 encapsulation to transport IPv6 packets inside IPv4 packets between the border gateway of the local network and the gateway servers outside.

6to4 is a public service, everybody can configure a gateway to use it - no subscription is necessary, since gateways will always know where to route responses based on the prefix. All 6to4 prefixes are in the 2002::/16 network and are /48 bits long (16bits for 2002::/16 and 32bits from the IPv4 address of the gateway). Unfortunately this service has become quite unreliable since public gateway servers seem to be unable to scale with the demand for prefixes.

6rd is the provider internal equivalent of 6to4. The provider establishes a gateway (or cluster of gateways) in its internal network and customer gateways are configured to use this gateway. The provider side prefix can be considerable longer than with 6to4 (/32 is normal), but it is also quite common to use only some bits of the IPv4 address - normally IPv4 addresses for customers are either assigned from a limited pool of public addresses (a /16 being the norm) or from one of the "private" pools (e.g. 10.0.0.0/8), so the leftmost bits of every customer IP will be identical and can be ignored. For this mechanism to work you have to be a subscriber of an ISP that provides this mechanism to its customers. The values that go into this calculation may or may not have some resemblance to what you can find out using the whois service, but the provider is free to use sub-nets, so you will need information directly from the provider.

Provider prefix IPv6: / Use 2002::/16 for 6to4 and whatever you ISP gave you for 6rd

Customer IPv4: IP: using bits; use your public IPv4 address (PPP: your own, not the peer address) and the bits value from the ISP or 32 for 6to4

IPv6 Customer prefix: /

convert the ISP prefix and public IPv4 to a IPv6 customer prefix
convert the IPv6 customer prefix to ISP prefix and public IPv4 (the provider prefix length will be used as is)

Teredo IP Decoding

Teredo client IP:

Teredo prefix:
2001::/32

Teredo server:
?

Teredo Flags:
?

Client public IPv4:
?

Client public UDP port:
?

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MAC -- EUI-64 Converter

With Auto-Configuration the 64-bit host ID (also called EUI-64 in IPv6 speak) of an IPv6 address is generated from the MAC address of the network card. This tool allows to convert between MAC and EUI-64.

48bit MAC: Please use dashes or colons to separate bytes

64bit Host ID: Please use IPv6 notation with ::/64 as prefix

Host Address

IP:	/
Network Prefix:	/
Host ID:
MAC:	00-11-22-33-44-55

JS Addr Calc revision 20120802
© Konrad Rosenbaum, 2012
This script is protected under the GNU GPL version 3 or at your option any newer.

Please mail patches to me (konrad@silmor.de) if you have any interesting additions for it.

0.0.0.0	the "ANY" address that is used by programs to speak to all network interfaces, it is never used directly. The whole network 0...* is reserved for special purposes (like DHCP).
10...* 172.16.. - 172.31.. 192.168..	are private addresses - you can use them freely within your own LAN. They will not be routed in the Internet.
127.0.0.1	is the localhost address, used by each host to talk to itself, there is always a special loopback interface preconfigured with this address, you never assign it to a real network device. The entire 127...* network is reserved for (host-)local networking.
169.254..	Link-Local addresses. These are automatically generated by some operating systems and (e.g. MacOS and Linux with Avahi installed) and are only usable for local communication in the LAN segment.
198.18.. - 198.19..	Network benchmark tests, this should never be used in production networks.
198.51.100.* 203.0.113.*	TEST-NET-2, Documentation and examples TEST-NET-3, Documentation and examples
224...*	Multicasts (former Class D network) - Warning: the data shown when you click this network is not completely accurate - e.g. there is no default gateway or broadcast for multicasting
240.0.0.0/4	Reserved (former Class E network)
255.255.255.255	Link Broadcast - this is sent to all hosts on the same network link, but does not cross routers

IPv4 Address:		Please use dotted decimal notation.
IPv6 Address:		Please use hexadecimal notation with the relevant 32 bits to the far right.

Provider prefix IPv6:	/ Use 2002::/16 for 6to4 and whatever you ISP gave you for 6rd
Customer IPv4:	IP: using bits; use your public IPv4 address (PPP: your own, not the peer address) and the bits value from the ISP or 32 for 6to4
IPv6 Customer prefix:	/

Teredo prefix:	2001::/32
Teredo server:	?
Teredo Flags:	?
Client public IPv4:	?
Client public UDP port:	?

48bit MAC:		Please use dashes or colons to separate bytes
64bit Host ID:		Please use IPv6 notation with ::/64 as prefix

Address Calculator

IPv4 Addresses

IPv4 to IPv6 Transitional

IPv4 in IPv6 Addresses

6to4 and 6RD Network Prefix

Teredo IP Decoding

IPv6 Addresses and Networks

MAC -- EUI-64 Converter

Host Address