PuTTY is an SSH and telnet client, developed originally by Simon Tatham for the Windows platform. PuTTY is open source software that is available with source code and is developed and supported by a group of volunteers.
The server has been designed to be secure in default configuration, it has no known vulnerability, it is really trivial to set up and it is especially designed for modern kernels. It was successfully ported to Linux, FreeBSD, Dragonfly BSD, NetBSD, OpenBSD, OSX, AIX and more.
Features include chroot()ed and/or virtual chroot()ed home directories, virtual domains, built-in ‘ls’, anti-warez system, configurable ports for passive downloads, FXP protocol, bandwidth throttling, ratios, LDAP / MySQL / PostgreSQL-based authentication, fortune files, Apache-like
log files, fast standalone mode, text / HTML / XML real-time status report, virtual users, virtual quotas, privilege separation, TLS and more.