CODEWITHSUNDEEP
httprequestresponse
March3April4
March3April4

Reputation: 2281

HTTP request to web server from client using private ips

I'm curious why a client(android or c# based program, etc) behind a private router(or gateway, anyway with a private ip such as 192.168.xx.xx) can get a response from a request to a http server.

I know that this works, but just want to know how.

Is the client which is getting back the response need port forwarding unless it's not using a public ip?

Upvotes: 2

Views: 2478

Answers (1)

Trim Kadriu
Trim Kadriu

Reputation: 451

He doesn't need port forwarding. This can work by using NAT or PAT (Network Address Translation or Port Address Translation) configured in the Router mostly configured by the ISP's in the edge router.

-EDIT (more explanation added):

The edge router has some public IP (mostly pool of IP's) configured to communicate in internet (public network). When the request that comes from internal network with private IP it takes that and changes the source IP (private IP) to one of the public IP's that has configured, thus the request would look like is made by the router itself.

Mostly will attach also a port number and save it in a database table (local db in router) with the private IP of the device who originally made the request and will forward the request to the internet.

Then, when the response is received by public server in that router, it will map it by the port with the private IP that had saved it in local db earlier, so it will know to whom it belonged originally, and will forward that to the IP

Upvotes: 1

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