The simplest form of remote login access is text-mode access, in which only textual data and a few simple control codes are exchanged between computers. Text-mode access is ideal for running text-mode programs, and it has the added advantage of consuming little in the way of network bandwidth, which makes it suitable to use across slow network links, such as dial-up Internet connections. This type of access can be very handy for administering a Linux system; Linux can be configured entirely using text-mode tools, so text-mode login methods can be a good way to do the job remotely. Perhaps your servers are scattered about the building (say, print servers located near the printers they manage) and you need to make changes without running around. Perhaps you need to log in over a dial-up line or even from a PDA while on the road. In such cases, remote administration is critical, and the ability to do the job without a lot of flashy (and bandwidth-intensive) GUI overhead can help you get the job done quickly. Remote text-mode access can also be useful for running many nonadministrative programs, although most ordinary users are more comfortable with GUI tools.
This chapter begins with a look at the principles behind text-mode loginstools for implementing it and why you might want to use it. This chapter then looks at two common protocols for implementing remote text-mode access, Telnet and the SSH, with a focus on Linux configuration. This chapter concludes with information on Windows tools for handling remote text-mode access, including both clients and servers.