In most cases, SSH is the preferred remote text-mode access method; this protocol implements security at its core, and it’s become almost as widely available as Telnet. SSH is, though, a much more complex protocol, and its server program implementations reflect this fact. Configuring and running an SSH server is therefore a more complex task than configuring and running a Telnet server, although the default SSH server configurations for most Linux distributions require little work to get running.
If you want to use SSH, you must first decide which of several SSH server packages to use:
SSH was developed by a company called SSH Communications Security (http://www.ssh.com), which sells its commercial SSH server under the name SSH Tectia. (Versions prior to 4.0 used the name SSH alone.)
This may be the most popular SSH server in Linux. It was originally
developed in association with OpenBSD, but most Linux distributions
include it under the package name
something similar. Its official web site is http://www.openssh.org, and
it’s distributed under the BSD license.
This server, headquartered at http://www.fressh.org, is an independent SSH implementation that’s distributed under the BSD license.
For GPL fans, lsh is an SSH implementation under that license. You can learn more at http://www.lysator.liu.se/~nisse/lsh/.
Any of these servers should work well and interoperate with common SSH client programs, ...