Remote desktop software carries one computer's screen and input to another over the internet. Three main parts work behind the scenes: an ID server, a relay server and the client.
1. ID and pairing
When the program starts, each computer gets an ID. The person connecting enters it, and the ID server introduces the two sides. The actual screen image does not have to pass through this server.
2. Direct (P2P) connection
If network conditions allow, the two computers connect directly. This lowers latency and keeps the picture smooth.
3. Relay fallback
If a firewall or network layout blocks a direct link, traffic goes through a relay server. The session stays encrypted.
4. Encryption
Session data is end-to-end encrypted with a public-key scheme based on NaCl/libsodium, so intermediate servers cannot read the content.
5. Video and input
The screen is compressed and streamed; mouse and keyboard events are sent back. File transfer and clipboard sharing use the same encrypted channel.
BirPencere keeps this simple on Windows: download, enter the ID and password, connect. See the features page for more.