What is a secure way of pairing a client and a server and ensuring that a request made has been from a client? My idea is to send a password with each request, but someone else on the network could sniff that data, even if it’s encrypted. They can then resend that packet and the server would think the correct PC has sent it. Even sending a hash wouldn’t work, since the attacker could just resend the hash.
The user will be running the server on one PC and the client will be another PC, but someone else could be on the same Wifi network. What’s a good way of trying to secure this sort of connection or is this not even possible?
Use SSL with mutual authentication.
You don’t need to pay for a certificate, you can be your own certificate authority and grant as many as you want.