Editing Secure Shell (section)

===Version 1===
In 1995, '''Tatu Ylönen''', a researcher at [[Helsinki University of Technology]] in Finland designed the first version of the protocol (now called '''SSH-1''') prompted by a password-[[Packet analyzer|sniffing]] attack at his [[university network]].<ref>{{cite web|author=Tatu Ylönen|url=https://www.scmagazineuk.com/the-new-skeleton-key-changing-the-locks-in-your-network-environment/article/545848/|title=The new skeleton key: changing the locks in your network environment|url-status=dead|archive-url=https://web.archive.org/web/20170820162632/https://www.scmagazineuk.com/the-new-skeleton-key-changing-the-locks-in-your-network-environment/article/545848/|archive-date=2017-08-20}}</ref> The goal of SSH was to replace the earlier [[rlogin]], [[TELNET]], [[FTP]]<ref>{{cite web|url=https://www.ssh.com/ssh/port|title=SSH Port|author=Tatu Ylönen|url-status=live|archive-url=https://web.archive.org/web/20170803235736/https://www.ssh.com/ssh/port|archive-date=2017-08-03}}</ref> and [[Remote Shell|rsh]] protocols, which did not provide strong authentication nor guarantee confidentiality. He chose the port number 22 because it is between <code>telnet</code> (port 23) and <code>ftp</code> (port 21).<ref>{{Cite web |last=Ylönen |first=Tatu |title=The story of the SSH port is 22. |url=https://www.ssh.com/academy/ssh/port |access-date=2023-11-30 |website=www.ssh.com |language=en}}</ref>

Ylönen released his implementation as [[freeware]] in July 1995, and the tool quickly gained in popularity. Towards the end of 1995, the SSH user base had grown to 20,000 users in fifty countries.<ref>{{Cite book |last1=Barrett |first1=Daniel J. |title=SSH, the secure shell: the definitive guide |last2=Silverman |first2=Richard E. |date=2001 |publisher=O'Reilly |isbn=978-0-596-00011-0 |edition=1st |location=Cambridge [Mass.] |page=11}}</ref>

In December 1995, Ylönen founded SSH Communications Security to market and develop SSH. The original version of the SSH software used various pieces of [[free software]], such as [[GNU Multi-Precision Library|GNU libgmp]], but later versions released by SSH Communications Security evolved into increasingly [[proprietary software]].

It was estimated that by 2000 the number of users had grown to 2 million.<ref name="Nicholas Rosasco and David Larochelle">{{cite web
 |author      = Nicholas Rosasco and David Larochelle
 |title       = How and Why More Secure Technologies Succeed in Legacy Markets: Lessons from the Success of SSH
 |publisher   = Dept. of Computer Science, Univ. of Virginia
 |work        = Quoting [[Daniel J. Barrett|Barrett]] and Silverman, SSH, the Secure Shell: The Definitive Guide, O'Reilly & Associates (2001)
 |url         = http://www.cs.virginia.edu/~drl7x/sshVsTelnetWeb3.pdf
 |access-date = 2006-05-19
 |url-status  = live
 |archive-url = https://web.archive.org/web/20060625065258/http://www.cs.virginia.edu/~drl7x/sshVsTelnetWeb3.pdf
 |archive-date = 2006-06-25
}}</ref>