OpenSSH

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OpenSSH (OpenBSD Secure Shell) is a set of computer programs providing encrypted communication sessions over a computer network using the ssh protocol. It was created as an open source alternative to the proprietary Secure Shell software suite offered by SSH Communications Security. OpenSSH is developed as part of the security conscious OpenBSD project, which is led by Theo de Raadt.[1] The project's development is funded via donations.

Contents

History

OpenSSH was created by the OpenBSD team as an alternative to the original SSH software by Tatu Ylönen, which is now proprietary software.[2] The OpenSSH developers claim that it is more secure than the original, due to their policy of producing clean and audited code and the fact, to which the word open in the name refers, that it is released under the open source BSD license. Although source code is available for the original SSH, various restrictions are imposed on its use and distribution.

OpenSSH first appeared in OpenBSD 2.6 and the first portable release was made in October 1999.[3]

Release History:

  • OpenSSH 5.6: August 23, 2010
  • OpenSSH 5.5: April 16, 2010
  • OpenSSH 5.4: March 8, 2010
    • Disabled SSH protocol 1 default support. Clients and servers must now explicitly enable it.
    • Added PKCS11 authentication support for ssh(1) (-I pkcs11)
    • Added Certificate based authentication
    • Added "Netcat mode" for ssh(1) (-W host:port). Similar to "-L tunnel", but forwards instead stdin and stdout. This allows, for example, using ssh(1) itself as a ssh(1) ProxyCommand to route connections via intermediate servers, without the need for nc(1) on the server machine.
    • Added the ability to revoke public keys in sshd(8) and ssh(1). While it was already possible to remove the keys from authorised lists, revoked keys will now trigger a warning if used.
  • OpenSSH 5.3: October 1, 2009
  • OpenSSH 5.2: February 23, 2009
  • OpenSSH 5.1: July 21, 2008
  • OpenSSH 5.0: April 3, 2008
  • OpenSSH 4.9: March 30, 2008
    • Added chroot support for sshd(8)
  • OpenSSH 4.7: September 4, 2007
  • OpenSSH 4.6: March 9, 2007
  • OpenSSH 4.5: November 7, 2006
  • OpenSSH 4.4: September 27, 2006
  • OpenSSH 4.3: February 1, 2006
    • Added OSI layer 2/3 tun-based VPN (-w option on ssh(1))
  • OpenSSH 4.2: September 1, 2005
  • OpenSSH 4.1: May 26, 2005
  • OpenSSH 4.0: March 9, 2005
  • OpenSSH 3.9: August 17, 2004
  • OpenSSH 3.8: February 24, 2004
  • OpenSSH 3.7.1: September 16, 2003
  • OpenSSH 3.7: September 16, 2003
  • OpenSSH 3.6.1: April 1, 2003
  • OpenSSH 3.6: March 31, 2003
  • OpenSSH 3.5: October 14, 2002
  • OpenSSH 3.4: June 26, 2002

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