Early services

Although the initial network architecture was peer-to-peer based the earliest applications used extensively, FTP (File Transfer Protocol, [FTP85]) and Telnet ([Tel83]), were based on the concepts of client and server. A server is a host providing a certain service and a client is a host using this service.

These applications were client/server applications, but the idea was to allow all hosts to work both as clients and servers. Any host accepted FTP and Telnet connections and were also able to connect to any other host. This made the Internet as a whole work as a peer-to-peer network.

Client/server protocols are usually based on the client sending a request to the server. The server manages the request and sends a response (sometimes called a reply) back to the client. Telnet, FTP and web browser clients work in this fashion. There are many more client/server based applications available and an exhaustive list would occupy most of this report.