How can I convert IPV6 address to IPV4 address

Question

I have application that uses IPv4 addresses  it stores them as long   so it only understands IPv4 addresses    Is it possible to convert IPv6 address to IPv4 with Java

User · Accepted Answer

While there are IPv6 equivalents for the IPv4 address range, you can't convert all IPv6 addresses to IPv4 - there are more IPv6 addresses than there are IPv4 addresses.

The only sane way around this issue is to update your application to be able to understand and store IPv6 addresses.

User · Answer

Some googling led me to the following post   http   www developerweb net forum showthread php t 3434  The code provided in the post is in C  but it shouldn t be too hard to rewrite it to Java

User · Answer

The IPAddress Java library can accomplish what you are describing here   IPv6 addresses are 16 bytes   Using that library  if you are starting with a 16-byte array you can construct the IPv6 address object   IPv6Address addr   new IPv6Address bytes     bytes is byte 16    From there you can check if the address is IPv4 mapped  IPv4 compatible  IPv4 translated  and so on  there are many possible ways IPv6 represents IPv4 addresses    In most cases  if an IPv6 address represents an IPv4 address  the ipv4 address is in the lower 4 bytes  and so you can get the derived IPv4 address as follows   Afterwards  you can convert back to bytes  which will be just 4 bytes for IPv4       if addr isIPv4Compatible      addr isIPv4Mapped              IPv4Address derivedIpv4Address   addr getEmbeddedIPv4Address            byte ipv4Bytes     derivedIpv4Address getBytes                         The javadoc is available at the link

User · Answer

Here is the code you are looking for in javascript  Well you know you can t convert all of the ipv6 addresses   lt script gt  function parseIp6 str        init   var ar new Array    for var i 0 i lt 8 i   ar i  0      check for trivial IPs   if str       return ar      parse   var sar str split         var slen sar length    if slen gt 8 slen 8    var j 0    for var i 0 i lt slen i           this is a       switch to end-run mode     if i  amp  amp  sar i       j 9-slen i continue       ar j  parseInt  0x0  sar i        j           return ar    function ipcnvfrom6 ip6      var ip6 parseIp6 ip6     var ip4  ip6 6  gt  gt 8       ip6 6  amp 0xff       ip6 7  gt  gt 8       ip6 7  amp 0xff     return ip4    alert ipcnvfrom6    C0A8 4A07      lt  script gt

User · Answer

There isn t a 1-1 correspondence between IPv4 and IPv6 addresses  nor between IP addresses and devices   so what you re asking for generally isn t possible   There is a particular range of IPv6 addresses that actually represent the IPv4 address space  but general IPv6 addresses will not be from this range

[java] How can I convert IPV6 address to IPV4 address?

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