“Thanks to the proliferation of packet sniffers and the
escalating reasons for data security and integrity, it should no
longer be acceptable to allow network logins to be sent in plain
text. By discovering passwords sent over the wire or hijacking
a connection via man-in-the-middle attacks, a malicious cracker
could quickly commandeer your network for her own nefarious
purposes. Luckily, a solution has been created, Secure Shell, which
replaces plain-text communication protocols, such as telnet, rsh,
and rlogin. Many other features are included besides
encryption, such as X11 forwarding (which allows secure use of X
applications across a network), port forwarding (allowing standard
TCP ports to be securely accessed), strong authentication,
authentication forwarding (allowing a single resource to hold
authorization information), Kerberos and AFS ticket forwarding, and
data compression.”
“Secure Shell, or SSH, was originally a free implementation
written by Tatu Ylonen. After restrictive licenses were placed upon
the code, Bjorn Gronvall decided to write a more open version of
the software, called OSSH. This caught the attention of the
developers of OpenBSD, already well known for their extensive
attention to security. Within a few months, OpenSSH 1.2.2 had been
released (and incorporated into OpenBSD 2.6). Many additions and
improvements were made to the previous version, including: all
patent-encumbered algorithms removed and replaced, support of ssh
1.5 protocol, support for Kerberos IV authentication, and far
leaner, cleaner, more secure code. The license is extremely
liberal, and may be used without charge for commercial and
non-commercial applications alike. The patent on RSA public-key
algorithm expires in September 2000, making both protocol versions
usable free of charge.”
“Development continued on OpenSSH, culminating on May 4, 2000
when OpenSSH 2.0 was released. OpenSSH 2.0 works with the ssh 1.3,
1.5, and superior 2.0 protocols, with the ability to automatically
adjust to the best performing protocol. Since then, development has
continued, particularly in the area of porting to other operating
systems. OpenSSH is now available for Linux, Solaris, HP/UX, Irix,
AIX, SCO, and NeXT.”