Command Line

SSH can automatically authenticate connections when the client presents an authorized key. A client gives it’s public key to a server and then when it connects the server knows it’s allowed in and automatically allows the connection. The Keys are specific to users, so a key for user_a will not let user_b in.

Few Simple Steps

1. Create Keys

   If the keys don’t exists already you must create them. Look in your ~/.ssh for files called id_rsa and id_rsa.pub. If those files don’t exist say ssh-keygen -b 2048 -t rsa to create them.

2. Place Keys on Server

   Copy id_rsa.pub to the server then append that to ~/.ssh/authorized_keys

Optionally you can use a DSA key, simply replace `rsa` with `dsa` above

The script automatically pushes your SSH private key to the server specified so you can have automatic SSH,scp and sftp authentication. If you don’t have a key the script will generate one for you, also this script assumes that the user running the script has a home directory on the remote host. Should note that this script will only push the RSA encrypted key.

The Script

#!/bin/bash

# say: ./ssh_script.sh hostname

# Uploads your id_rsa.pub to the specified host, wrapped for readability

if [ ! -r ${HOME}/.ssh/id_rsa.pub ];then

ssh-keygen -b 2048 -t rsa

fi

# Append to the copy on the remote server

cat ~/.ssh/id_rsa.pub | ssh ${USER}@$1 “cat – >> .ssh/authorized_keys”

if [ $? -eq 0 ]; then

echo “Success”

fi

save the script say as  ssh_script.sh and execute it ./ssh_script.sh hostname