What's the difference between an ip address and a local ip address?

Question

I was looking at ipleaks.net and my ip address and local ip address are different. Can anyone explain to me why and what's the difference?

Answer 1

When the Internet started in the 1990s, the IP addresses were defined using 32 bits to give a total of around 4 billion different addresses. At the time this seemed reasonable, but the demand for addresses has outstripped the number of addresses that 32 bits can offer. These were called IPv4 addresses. Two solutions exist for this problem. One is to increase the number of addresses available, which isadually being rolled out by moving to IPv6 addresses with 128 bits or around 256 billion billion billion billion addresses; however, many devices in the world are not capable of working with IPv6. The other alternative is a technique called Network Address Translation (NAT).



In the early days it was theoretically possible for every computer using the Internet to have its own unique address, but as there are more devices than addresses, NAT provides a convenient solution as an interim before IPv6 takes over completely. With NAT, it is only the router that needs to be aware of the problem. It provides a private local network for all your computers (and other devices) each with its own private local IP address, and the router maps all these device on to a single public IP address to use on the Internet. This allows far more devices to use IPv4 addresses than the 32 bit address range will allow without NAT. This is because each private local address range provided by each router can use the same range of addresses.



The analogy is blocks of apartments. To different blocks will have their own unique postal address, but the flats can be numbered simply as apartment 1, apartment 2, etc in each block. The postal address is like the public IP address, while the apartment numbers form the private network addresses that can be duplicated at different public addresses.



The site ipleak.net (not ipleaks.net) shows the public IP address first, then the next one is the local (private) IP address that is actually configured on the computer.



I hope this helps.

Answer 2

ok so firstly the normal ip address you are referring to is actually an external ip address assigned for use by your internet service provider (ISP) for when you connect to the internet.on the other hand your local ip address is the ip address assigned by a router for instance on a private home network however with the local ip address it is subject to change epending on what other devices are connected to the same network and in what order they were connected. Most network routers assign IP addresses starting at 192.168.1.2, and increment the last digit with each new device that connects. Note* Your local IP address is hidden from the outside world and used only inside your private network. You generally don't need to know much about it unless you're trying to set up a game or web server.



I hope i helped :)

Answer 3

Local IP = the address on your local network (i.e. behind your modem)



Public IP = the address of your modem on the internet

Answer 4

So by now you know about private and public IPs. The router uses Network Translation (NAT) to hide the private IP behind the public.



Suppose I go to a website, port 80, www.mydomain.com.



From your private ip (192.168.1.2) I open a connect www.mydomain.com. Clients use a high port > 512, random to talk outside. So your browser is using, say port 1025 connecting to www.mydomain.com port 80.



The router intercepts that because of NAT. It maps your public ip and port to a random port of the router. So outbound from the router, it uses your public ip and say port 1025.



So 192.168.1.2/1024 -> router's IP port 1025 -> connects to www.mydomain.com port 80.



Coming back it know things destined for routers public ip port 1025 is going to you, 192.168.1.2/1024 (that is why it maps it).



So back



www.mydomain.com/80 -> routers public ip/1025 -> 192.168.1.2/1024 (your browser)



This also why you need port forwarding to host anything, why you need UPnp , why you need to specify any inbound connection. The inbound mapping translation is not defined unless you define it or UPnp does it for you.

Answer 5

Your local IP address is one allocated to you by your home router (likely 192.168....)

Your IP address is one allocated by your ISP and is globally unique.