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OpenSSH, also known as OpenBSD Secure Shell, is a suite of security-related network-level utilities based on the SSH protocol, which help to secure network communications via the encryption of network traffic over multiple authentication methods and by providing secure tunneling capabilities. OpenSSH started life as a fork of the free SSH program, developed by Tatu Ylönen; later versions of Ylönen's SSH were proprietary software, offered by SSH Communications Security. OpenSSH was first released as part of the OpenBSD operating system in 1999. OpenSSH is not a single computer program, but rather a suite of programs that serve as alternatives to unencrypted network communication protocols like FTP and Rlogin. Active development primarily takes place within the context of OpenBSD; a dedicated team occasionally releases a version that can be ported or used in other operating systems. This has allowed OpenSSH and its derivatives to account for an almost 88% market share .〔(【引用サイトリンク】url=http://www.openssh.com/usage/graphs.html )〕 == History == OpenSSH was created by the OpenBSD team as an alternative to the original SSH software by Tatu Ylönen, which is now proprietary software.〔(【引用サイトリンク】 Project History and Credits )〕 Although source code is available for the original SSH, various restrictions are imposed on its use and distribution. OpenSSH was created as a fork of Björn Grönvall's OSSH that itself was a fork of Tatu Ylönen's original free SSH 1.2.12 release, which was the last one having a license suitable for forking. The OpenSSH developers claim that their application is more secure than the original, due to their policy of producing clean and audited code and because it is released under the BSD license, the open source license to which the word ''open'' in the name refers. OpenSSH first appeared in OpenBSD 2.6. The first portable release was made in October 1999.〔 Developments since then have included the addition of ciphers (e.g., chacha20-poly1305 in 6.5 of January 2014), cutting the dependency on OpenSSL (6.7, October 2014) and an extension to facilitate public key discovery and rotation for trusted hosts (for transition from DSA to Ed25519 public host keys, version 6.8 of March 2015). On October 19, 2015 Microsoft announced that OpenSSH will be natively supported on Windows and accessible through Windows PowerShell, releasing an early implementation and making the code publicly available.〔(【引用サイトリンク】title= OpenSSH for Windows Update )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「OpenSSH」の詳細全文を読む スポンサード リンク
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