Secure Shell

Secure Shell (or SSH) is a set of standards and an associated network protocol that allows establishing a secure channel between a local and a remote computer. It uses public-key cryptography to authenticate the remote computer and (optionally) to allow the remote computer to authenticate the user.

SSH without passwords

• Step 1: Generate keys (public and private) and leave passphrase blank if you want password-less logins:

ssh-keygen -t dsa

Or,

ssh-keygen -t dsa -b 2048 -f /home/bob/my-key

• Step 2: Copy public key to remote server (Important: Only the public key!):

scp ~/.ssh/id_dsa.pub username@hostname:.ssh/authorized_keys

• Step 3: Set directory/file permissions (if not already set):

chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys

• Step 4: Now, SSH into your remote server (password will be required the first time):

ssh username@hostname

That's it! You are now free to log into your remote server without entering a password. This is useful for automating file transfers. However, it must be used with care. If not executed properly, it is a potential security risk.

See also

• SSH Filesystem (sshfs)
• Fish protocol
• rsync

External links

• Wikipedia article on SSH
• Copying mass amounts of data over a network with bash, rsync, and ssh