With tinc you can create a virtual private network (VPN) that lets you communicate between two machines over an insecure network such as the Internet with all of your traffic encrypted between the hosts on your virtual network.

Another interesting application for tinc is connecting your laptop to a Wi-Fi router at home. You might already be using WPA2 to ensure that only valid hosts can connect and communicate with your Wi-Fi router, but you might not be able to assign a fixed address to the laptop when it is connected over Wi-Fi. So if you want to connect to an SSH daemon on the laptop itself or access an NFS share on the laptop, you have to play guessing games as to which IP address the Wi-Fi router has given the laptop this time. Running tinc on the laptop and a server at home removes the guessing game -- just connect to the laptop's VPN IP address. This is an interesting article for anyone who is thinking about setting up an VPN. It talks about using a tool called tinc.

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