With the massive growth in internet devices, shouldn’t we have used up all possible ipv4 numbers?
In: Technology
A technique called NAT helped out with that. It’s basically used everywhere both for business and in homes. Fiber connections aside, it’s also a contributing reason why we call the box at home ‘router’ and not ‘modem’ anymore (even though modem functionality may be built in for cable connections).
NAT works like telephone switchboard. Let’s say you call customer service at a major company, there could be 200 people answering the phone but there’s not 200 numbers listed under ‘Contact us’. There is one number that you call and then it’s split up internally. If they call you back, you typically only see their shared number, the one you called, displayed on your phone, not the individual number for the individual operator. Internally, if they need to call a colleague or manager they can use short numbers (“extensions”) like 0046 that doesn’t work outside their telephone system.
Connected devices work similar in a NAT:ed network. They get unique internal addresses and they can share “real” public IPv4 addresses for external connections. The router keeps track that device ABC asked for www.reddit.com, so all cat pictures from that connection should go back to that device. There are three ranges for internal use, with the vast majority of devices for private use is configured to use addresses looking like 192.168.0.x. So it’s likely that a number of people in any Reddit thread may actually have the same private IP address, but everyone in their own closed context “behind” their public address.
Latest Answers