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OpenSSH is a compatible, free open source implementation of the original SSH protocol. It enables you to replace obsolete, insecure protocols and services (like Telnet, rlogin/rsh/rcp), or – if a replacement is not possible – to provide additional security for them (via tunneling).

You can open terminal sessions, X sessions or copy data. Therefore SSH is often used for remote maintenance.

Main features:1)

  • Strong Encryption
  • X11 Forwarding (encrypt X Window System traffic)
  • Port Forwarding (encrypted channels for legacy protocols)
  • Strong Authentication (Public Key, One-Time Password and Kerberos Authentication)
  • Agent Forwarding (Single-Sign-On)
  • SFTP client and server support in both SSH1 and SSH2 protocols.
  • Kerberos and AFS Ticket Passing
  • Data Compression

The main tools provided by OpenSSH are:

  • sshd – The OpenSSH server daemon/service
  • ssh – The OpenSSH client
  • scpsecure copy, similar to cp
  • sftpsecure file transer programm, similar to ftp

Other important parts:

  • ssh-add
  • ssh-agent
  • ssh-askpass
  • ssh-copy-id2)
  • ssh-keygen – Generates SSH keys
  • ssh-keyscan
  • ssh-argv0


For the sake of clarity, information about the different OpenSSH tools and types of use are distributed over single pages:

See also

  • Seahorse – Comfortable GUI to manage your GnuPG and SSH keys.
  • putty – Cross platform terminal emulator (SSH/Telnet/rlogin/raw TCP) including session management GUI.
  • FileZilla – Free and fast (S)FTP client with GUI.
mainly Debian/Ubuntu – other systems may not provide this command
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