We have a router (Router 2) inside a network (Router 1) with a client (Client in Router 2) that needs to make a TCP connection to a client in router 1. We only have access to configure Router 2 and the IP address of the client in Router 1 can change. How do we configure Router 2?

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  • Welcome to Network Engineering! This question sounds very much like a school assignment or homework problem, which is off-topic here. If not, we would need more information. Are R1 and R2 directly connected, or is there an intermediate network(s) between them? – Ron Trunk Oct 11 '18 at 13:44
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    @RonTrunk Its not for school its a legitimate question. I just tried to phrase is as simply as possible to make people life easier to answer. R1 and R2 are directly connected (as shown on the diagram) – ianj Oct 11 '18 at 13:57
  • Client 2 will need the address of Client 1 to initiate a TCP connection with Client 1. It must send a SYN to Client 1 at its IP address to start the TCP connection. For example, you do not know my IP address, so you could not initiate a TCP connection with my PC. – Ron Maupin Oct 12 '18 at 14:25

R2's configuration doesn't need to change, but client 2 needs to know the address of client 1, or it needs to resolve the DNS name for it.

It would be the same problem if there were no routers between client 1 and client 2.

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  • Hi Ron, thanks for your answer. We do have the ip address of client 1, when we try to open a tcp connection from client 2 to client 1 using that ip address, it doesn't work. – ianj Oct 12 '18 at 10:55
  • Perhaps you can provide more specifics. Maybe the problem isn’t your router. – Ron Trunk Oct 12 '18 at 11:13

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