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Basic data

developer The OpenBSD project under Theo de Raadt
Publishing year 1999
Current  version 8.3
( May 27, 2020 )
operating system Unix , Microsoft Windows Server
programming language C.
category Remote access
License BSD license
German speaking No
SSH session on remote computer
ssh-keygen when generating keys
ssh-keyscan when scanning

OpenSSH is a file transfer package . It uses Secure Shell (SSH) including SSH File Transfer Protocol and includes clients , utilities and a server .


OpenSSH was created in 1999 as a spin-off of an older implementation of the SSH protocol from Tatu Ylönen , when it was still free software . OpenBSD programmers simplified this derivative by Björn Grönvall, brought it up to date with the current state of the protocol, and published their first own version as OpenSSH 1.2.2.

OpenSSH was also available for FreeBSD and Linux at the premiere as part of OpenBSD . OpenSSH now works on almost anything remotely Unix , including Cygwin .

Companies like IBM and Hewlett-Packard offer OpenSSH for their operating systems like AIX and HP-UX with extensions, and Microsoft also offers OpenSSH for Windows Server 2019 .


The licensing of OpenSSH is confusing because several licenses have been taken over, which ultimately equals the original BSD license . OpenSSH uses LibreSSL for many encryption functions .


OpenSSH includes:

  • ssh (as a replacement for rsh , rlogin and telnet )ssh
  • scp (as a replacement for rcp)scp .
  • sftp (as a replacement for ftp )sftp
  • sshd (the SSH daemon ) includes scp and sftp serverssshd
  • ssh-keygen (authentication key generator, management and conversion) ssh-keygen
  • ssh-keyscan (capture of SSH public keys) ssh-keyscan
  • ssh-agent (keeps the private key in memory) eval `ssh-agent`
  • ssh-add (loads a private key into the ssh-agent) ssh-add ~/.ssh/id_rsa

Additional functions

In addition to the main task of remote access, OpenSSH offers additional functions such as port forwarding . With port forwarding, the client can open a local port and forward TCP traffic through the server to a remote destination. This can e.g. B. can be used to access protected resources within a network with OpenSSH, without setting up a VPN . Port forwarding can also be done in the opposite direction, with the server receiving access to the client's environment.


The development of OpenSSH is divided into two teams. The first team develops only for OpenBSD, in order to keep its code as simple and secure as possible. The second team adds a variant to OpenSSH with the letter p in the version designation, which can be used on other implementations of Unix and Unix-like systems .


  • Daniel J. Barrett, Richard E. Silvermann: SSH. Secure Shell. A comprehensive manual. (Network security). O'Reilly Beijing et al. 2002, ISBN 3-89721-287-0 (English: SSH, the Secure Shell. The definitive Guide. (Securing your Network and Services). 2nd edition. Ibid 2005, ISBN 0-596-00895-3 ).
  • Timo Dotzauer, Tobias Lütticke: The SSH book. Guide to the secure use of OpenSSH. Millin, Lohmar 2007. ISBN 3-938626-03-8 .
  • Michael Stahnke: Pro OpenSSH, (Take Advantage of OpenSSH, the World's most popular SSH Protocol Implementation, to secure your Network). Apress, Berkeley CA 2006, ISBN 1-59059-476-2 ( The Expert's Voice in open Source = Books for Professionals by Professionals ).

Web links

Individual evidence

  1. . May 27, 2020.
  2. .
  3. The openssh Open Source Project on Open Hub: Languages Page . In: Open Hub . (accessed on July 18, 2018).
  4. ^ Project History and Credits . OpenBSD Foundation. Retrieved February 12, 2012.
  5. OpenBSD 2.6 release . OpenBSD Foundation. Retrieved February 12, 2012.
  6. ^ Systems using OpenSSH . OpenBSD Foundation. Retrieved February 12, 2012.
  7. OpenSSH is now bundled with AIX . IBM. Retrieved February 12, 2012.
  8. HP-UX Secure Shell . Hewlett-Packard. Retrieved February 12, 2012.
  9. Installation and Useage of Win32 – OpenSSH . Microsoft. Retrieved December 13, 2018.
  10. LICENSE . OpenBSD Foundation. Retrieved February 12, 2012.
  11. Project goals . OpenBSD Foundation. Retrieved December 17, 2017.
  12. The Portability of OpenSSH . OpenBSD Foundation. Retrieved February 12, 2012.