Igor at ritlabs
Aug 26, 2004, 1:28 AM
Views: 1077
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My server is in IPv4 network. We can get following SPF record:
v=spf1 ip6:0:0:0:0:0:FFFF:192.168.1.128 -all
How to convert sender's IPv4 address to IPv6?
Rfc2373 defines two forms of such convertion:
---< from rfc2373>---
The IPv6 transition mechanisms [TRAN] include a technique for hosts
and routers to dynamically tunnel IPv6 packets over IPv4 routing
infrastructure. IPv6 nodes that utilize this technique are assigned
special IPv6 unicast addresses that carry an IPv4 address in the low-
order 32-bits. This type of address is termed an "IPv4-compatible
IPv6 address" and has the format:
| 80 bits | 16 | 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|0000| IPv4 address |
+--------------------------------------+----+---------------------+
A second type of IPv6 address which holds an embedded IPv4 address is
also defined. This address is used to represent the addresses of
IPv4-only nodes (those that *do not* support IPv6) as IPv6 addresses.
This type of address is termed an "IPv4-mapped IPv6 address" and has
the format:
| 80 bits | 16 | 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|FFFF| IPv4 address |
+--------------------------------------+----+---------------------+
---< end >---
What form should be used?
- Igor
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IPv4 to IPv6 convertion
