Terminal servers were originally designed for connecting terminals to minicomputers. Each terminal would have an RS-232 port. The connection to the minicomputer usually used an ethernet port. Connecting terminals would be connected to a command line interface where they could select from a list of predefined machines. A Telnet session would then be started to that machine.
Over time terminal servers gained more features. For example, modems could be connected. These initially allowed people to dial in to the minicomputer but grew in features until most terminal servers became routers with a great number of serial ports.
As well as allowing the connection of many console to a single terminal, the terminal server can be configured with user accounts and passwords, preventing unauthenticated access to the console whilst still allowing the console to be reached from any modem.
This remainder of this section lists the considerations when purchasing terminal servers and the cabling pinouts and basic software configuration needed for differing types of terminal servers.
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