View source for SSH - Client and Server

== A little script to enable passwordless login==
Needless to say, that using this script you should '''exactly''' know what you are doing.

!! The author takes '''NO''' response for all kinds of damage and security issues that could happen using this script !!

=== Download ===
* [https://wiki.blue-it.org/images/Ssh_export_pub_key_for_passwordless_login.sh.zip Ssh_export_pub_key_for_passwordless_login.sh.zip]

=== Source Code ===

 #!/bin/bash
 #
 cat <<EOF
 ---------------------------------------------------------------------
 This scripts exports THIS computers public ssh key to
 a clients's ~/.ssh/authorized_keys2 file.
 
 This will enable passworless login from THIS pc to the client.
 
 You need to specify at least the IP/alias of the other pc!
 You optionally can specify another username than the actual one.
 
 Usage: ssh_export ip_of_remote_client  [alternate_username]
 ---------------------------------------------------------------------
 
 EOF
 
 client="$1"
 NAME="$2"
 THIS_HOSTNAME="$HOSTNAME"
 
 [ "$NAME" ] || NAME="${USER}"
 [ "$client" ]  || echo "ERROR: You have to specify at least a client IP or alias."
 [ "$client" ]  || exit 1
 
 cd ~/.ssh
 
 echo -n "* Check connection to client ... "
 if ping -c 1 $client > /dev/null
 then
 	echo OK.
 else 
 	echo Please check the connection.
 	echo   - Aborting here.
 	exit 1
 fi
 
 echo "* Create ssh dir on client, if it not already exists ... "
 ssh ${NAME}@$client "mkdir -p ~/.ssh; chmod 700 ~/.ssh"
 
 echo "* Check if a local pub key exist and/or create one ... "
 PUB_KEY="id_dsa.pub"
 if test -e $PUB_KEY
 then
 	echo "   - A file named $PUB_KEY exists."
 else
 	echo "   - Creating a new one."
 	ssh-keygen -t dsa 
 fi
 
 echo "* Check, if an older key was exported already in former time to the client."
 if
         ssh ${client} "if (cat ~/.ssh/authorized_keys2 | grep ${NAME}@${THIS_HOSTNAME});\
                 then echo  - WARNING: An older key was exported before to $client. \
 			\n  - Please fix manually.; exit 1; \
                 fi";
 then
         echo "  - Authorized keys file is clean."
 else 
 	echo "  - Aborting here."
 	exit 1
 fi
 
 echo "* Copy the public key of THIS pc to the client ... "
 scp id_dsa.pub ${NAME}@$client:~/.ssh/id_dsa.pub_${HOSTNAME}
 
 echo "* We make an entry into the authorized_keys file on the client ... "
 ssh ${NAME}@$client "cat ~/.ssh/id_dsa.pub_${HOSTNAME} >> ~/.ssh/authorized_keys2; \
    rm ~/.ssh/id_dsa.pub_${HOSTNAME};"
 
 echo "* Secure the local public key ... "
 chmod 600 id_dsa.pub
 
 echo ;
 echo "* LET'S TEST IT:"
 echo "  Now we test with running the following terminal command."
 echo "  You should NOT be prompted by a password."
 echo ;
 
 if
         ssh ${NAME}@$client "echo   - This is a message on $client."
 then 
         echo "  - Congratulation: If you was NOT promptd for a password,"
 	echo "     you can login passwordless to your client $client."
 else
 	echo "  - WARNING: There was an error with the passwordless login to $client."
         exit 1
 fi
 
 echo ;
 echo ;
 echo "** Program ended."
 echo ;
 echo If you like to remove the automatic login, you have to 
 echo remove the public key in the file /home/${NAME}/.ssh/authorized_keys2
 echo on your clients - $client - computer.