SSH, the Secure Shell/Introduction to SSH

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Introduction to SSH[edit]

What is SSH[edit]

SSH, the Secure Shell is a safe replacement for telnet, rcp and ftp. It has a client/server architecture. When data is sent via SSH, it is automagically encrypted, and then decrypted on the other side, making it unsniffable for crackers. Thanks to the SSH suite, we can safely log in remotely, copy files, or even (via tunneling) make other services (http, pop) safe! UNIX SSH packages include a server and a client. On Windows there mostly is no need for a server.

Features of SSH[edit]

  • Secure remote login
ssh some.host
  • Secure remote command execution
ssh some.host w
  • Secure file transfer
scp some_file some.host:some_file
scp -R some_directory some.host:some_directory
sftp some.host
  • Port forwarding
ssh -L 8080:localhost:80 some.http.server
  • Access control (give someone access to only some particular programs on your account)

History[edit]

In 1995, Tatu Ylönen, a researcher at Helsinki University of Technology, Finland, designed the first version of the protocol (now called SSH-1) prompted by a password-sniffing attack at his university network. The goal of SSH was to replace the earlier rlogin, TELNET and rsh protocols, which did not provide strong authentication or guarantee confidentiality. Ylönen released his implementation as freeware in July 1995, and the tool quickly gained in popularity. Towards the end of 1995, the SSH user base had grown to 20,000 users in fifty countries.

You can read more about history of SSH at wikipedia:Secure Shell#History and development.

PGP and GPG[edit]

PGP and GPG are similar to SSH programs. They are mostly used to electronically sign and encrypt e-mail messages, but can also be used to encrypt files, or communicators.