SSH (Secure Shell) Home Page

SSH (Secure Shell) is a software package that enables secure system administration and file transfers over insecure networks, such as the Internet.

History of the SSH Protocol

ssh inventor Tatu Ylonen

The Secure Shell protocol was developed by Tatu Ylonen in 1995, originally in response to a hacking incident in the Finnish university network. A password sniffer had been installed on a server connected directly to the backbone, and when it was discovered, it had thousands of usernames and passwords in its database, including several from Ylonen's company.

That incident triggered Ylonen to study cryptography and develop a solution he could use himself for remote login over the Internet safely. His friends proposed additional features, and three months later, in July 1995, Ylonen published the first version as open source. It became OpenSSH. Later he took the protocol for standardization at the IETF and designed the SSH File Transfer Protocol (SFTP).

Ylonen still works on topics related to Secure Shell, particularly around key management, as well as broader cybersecurity topics.

Today, the protocol is used for managing more than half of world’s web servers and practically every Unix or Linux computer, on-premise and in the cloud. Information security specialists and system administrators use it to configure, manage, maintain, and operate most firewalls, routers, switches, and servers in the millions of mission-critical networks and environments of our digital world. It is also embedded inside many file transfer and systems management solutions.

The new protocol replaced several legacy tools and protocols, including telnet, ftp, FTP/S, rlogin, rsh, and rcp.

The Company behind the Product

At the end of 1995, Ylonen founded to provide commercial support for Secure Shell. The company is now one of the leading server-side security solution providers for enterprises.

The company has made countless contributions to the greater good with the security standardization efforts in the IETF. The IETF standards for PKI, Secure Shell, IPsec, and NAT Traversal (STUN, SIP, etc) are heavily influenced by the efforts of the company.

The company serves the most demanding customers in the public and private sectors. It has over 3000 customers including top-10 banks, numerous Fortune 500 enteprises, and governments.

Today, the company is the market leader in managing Secure Shell keys and policy enforcement and audit for Secure Shell.

The technologies and inventions of the company are deeply embedded and represented in today’s digital world. Telecommunications infrastructure, smartphones, tablets, and other portable computing devices use the NAT Traversal technology patented by the company.

Origin of the Protocol and Current Issues Around It, by Tatu Ylonen