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--- en:network_terms:network_address_translation [2022-04-02-11-07] – 7saturn
+++ en:network_terms:network_address_translation [2022-04-02-11-07] (current) – [Mechanism] 7saturn
@@ Line 6: / Line 6: @@
 As you can imagine, 4 Billion Computers may sound a lot at first, but since nowadays many people have more than one computer device (one tablet, a smartphone, a PC, maybe a console, and you already have four devices in use, not counting the [[server|servers]] you are connecting to), this number quickly was identified as a little to short. IPv6 uses 128 bits of address space, which leads to a theoretical astronomical number of hosts of around 3 times 10 to the power of 38. That solves the problem with the address space once and for all. But as both protocols are still used, the old IPv4 still needed a solution for the problem of a lack of available addresses. If everyone had all the used devices on the public internet, the address space would have been exhausted years ago. The solution comes in form of a translation mechanism, that is usually facilitated by your router.
 ===== Mechanism =====
-The router takes the function of a gateway, meaning, all internet connections have to go through it. Your local network is separated from the rest of the internet. It is using its own [[subnet]], its own IP address space. Usually so-called [[..:network terms:private_addresses]] are used, that are not routed through the internet (making them technically not reachable over the internet, but only on the local network). This way, certain IP addresses can be re-used for every one at home. They don't interfere with the rest of the internet.
+The router takes the function of a gateway, meaning, all internet connections have to go through it. Your local network is separated from the rest of the internet. It is using its own [[subnet]], its own IP address space. Usually so-called [[..:network terms:private addresses]] are used, that are not routed through the internet (making them technically not reachable over the internet, but only on the local network). This way, certain IP addresses can be re-used for every one at home. They don't interfere with the rest of the internet.
 But as this is kind of a separated, unreachable network, how do computers communicate to and with those, anyways? The answer lies in the Network Address Translation concept. Your router works as NAT. In principle, the following happens: Every package that is sent from your local network get's stripped of its source address (sender) and source port. Both are replaced with the address of the router on the other side, the internet, and another port. The router remembers which source address and port combination he gave which port on the internet side.