How is the connection to the internal network from the outside?

Question

Computer networks

I ask as a beginner in computer networks.
Interested in how specifically the connection to a specific device in the local network from the outside (from the global one) occurs. that is, if we have a white ip, we can connect, for example, to an ip camera, but how does the router redirect the request, without specifying which of the local ip addresses the connection is made to?

Answer 1

but how does the router redirect the request, without specifying which of the local ip addresses the connection is made to?

No indication, nothing.
But there is guidance in one form or another.
If the internal network has gray addresses, then NAT is configured on the router and the port forwarding rule is written there - this rule is the indication of the local address.
If white addresses are used within the network (relevant for IPv6, well, sometimes the same can be found in IPv4), then the routing table contains the corresponding rules.

Answer 2

but how does the router redirect the request, without specifying which of the local ip addresses the connection is made to?

It's all done in the router settings.

Answer 3

uPNP allows you to do port forwarding automatically , provided that the router supports it.
Then outwardly it looks like this - nothing was configured, but everything works

Answer 4

NAT has existed for more than a year and there is no special magic in it.
Specifically, if there is an external routable address in the router settings, there is an indication of the target host.
Moreover, in some camera models, a white address is not needed. The camera connects to the manufacturer's service outside the local network and sends the picture there.

Answer 5

Usually through a VPN to protect traffic between the camera (or whatever is there) and the user
. But there is also port forwarding through NAT - in this case, traffic protection can also be provided if it is provided by the program being accessed