ssh to a server without typing your password

ssh-tutorial.md

How to ssh to a remote server without typing your password

Save yourself a few keystrokes. Follow the steps below:

1. Run this Bash script on your laptop:

   #!/usr/bin/env bash
   
   # The hostname of your remote server.
   host=myserver.com
   
   # Create this folder if it does not exist: ~/.ssh
   mkdir ~/.ssh
   
   # Set the correct permissions (required)
   chmod 700 ~/.ssh
   
   # Generate an RSA key pair for identification with the remote server
   ssh-keygen -t rsa
   
   # Copy your public key to the remote server
   cat ~/.ssh/id_rsa.pub | ssh $host 'cat >> ~/.ssh/authorized_keys'
   
   # ssh is very strict about correct permissions
   ssh $host 'chmod g-w,o-w ~; chmod 700 ~/.ssh; chmod 600 ~/.ssh/authorized_keys'

   At this point, you can connect to your server without typing a password:

   ssh username@myserver.com

2. If you would prefer to type jupiter (7 characters) rather than username@myserver.com (21 characters), create a config file ~/.ssh/config on your laptop, as shown below. You'll be able to use the jupiter alias with: rsync, scp, and ssh.

   # ~/.ssh/config
   
   Host jupiter
       User carl
       HostName myserver.com
   

   At this point, you can connect to your server like this:

   ssh jupiter

3. If you want a single command to do two steps:

   1. First, connect to a login server jupiter
   2. Next, connect to a work server saturn

   Then configure your ~/.ssh/config file as follows:

   # ~/.ssh/config
   
   Host jupiter
       User carl
       Hostname myserver.com
   
   Host saturn
       User carl
       ProxyCommand ssh -qX jupiter nc %h %p
   

   At this point, you can connect to saturn via jupiter like this:

   ssh saturn

Further reading

How to write your own config file:

• http://www.cyberciti.biz/faq/create-ssh-config-file-on-linux-unix/

All available configuration options:

• http://linux.die.net/man/5/ssh_config