For Telnet, it is an indispensable assistant for administrators. In some remote operations, we can use Telnet for management. Therefore, you cannot be unfamiliar with the Telnet server. So let's take a look at the content in this area.
The working process of remote login
When using the Telnet protocol for remote login, the following conditions must be met: there must be a client program containing the Telnet protocol installed on your computer; you must know the IP address or domain name of the remote host; and you must know the login identifier and password.
Telnet remote login service is divided into the following four processes:
1) Establishing a connection between the local and remote hosts. This process actually establishes a TCP connection, and the user must know the IP address or domain name of the remote host;
2) Sending the username and password entered on the local terminal and any subsequent commands or characters in NVT (Net Virtual Terminal) format to the remote host. This process is actually sending an IP datagram from the local host to the remote host;
3) Converting the NVT formatted data output by the remote host into a format accepted locally and sending it back to the local terminal, including command input echo and command execution results;
4) Finally, disconnecting the connection from the remote host by the local terminal. This process involves terminating a TCP connection.
Telnet is a remote login program, consisting of a Telnet client program running on the user's local computer (client side) and a Telnet server program running on the remote computer to be logged into (server side). The client-installed client program is terminal software that can issue requests, while the server-installed server program has the function of responding to login requests, and both follow the same network terminal protocol.
Using remote login, you can access the resources of a remote host as if you were one of its terminal users. However, it requires having a fully functional account (username and password) on the remote host.
When accessing a Telnet server site, the following three items are needed:
1. Address of the Telnet client
This is usually the host address, sometimes also the IP address, indicating that the user has connected to the Internet network. If it's a dial-up user, they can automatically obtain a dynamic IP address.
2. Port number
Sometimes, the Telnet server being logged into needs to handle multiple Telnet sessions simultaneously. Using ports allows users to find the corresponding Telnet connection.
3. Address of the Telnet site
Telnet is a remote login program, consisting of a Telnet client program running on the user's local computer and a Telnet server program running on the remote computer to be logged into.
The purpose of Telnet is to allow users to log into a certain host on the Internet in a simulated terminal manner. Once the connection is successful, these personal computers become like a terminal of the remote computer, allowing commands to be entered and programs on the remote computer to be run just as if using their own computer.
Article source: 【Eden Network】http://www.edenw.com/tech/net/col/2010-07-20/4821.html