Autologin through SSH using bash script

Autologin using bash script

1. Create a new ssh RSA keygen:

[root@linuxtutors# ~]# ssh-keygen -t rsa

Generating public/private rsa key pair.

Enter file in which to save the key (//.ssh/id_rsa):

Enter passphrase (empty for no passphrase):

Enter same passphrase again:

Your identification has been saved in //.ssh/id_rsa.

Your public key has been saved in //.ssh/id_rsa.pub.

The key fingerprint is:

4a:0d:db:6a:06:c9:c8:62:e0:f3:cb:93:5f:de:d6:f4 root@-i

Keys are stored at /.ssh/ directory:

[root@linuxtutors# ~]# cd /.ssh/

List the files

[root@linuxtutors# .ssh]# ls -l; cd

total 6

-rw-------   1 root     root         883 Apr  4 17:50 id_rsa

-rw-r--r--   1 root     root         217 Apr  4 17:50 id_rsa.pub

-rw-r--r--   1 root     root         633 Apr  4 17:43 known_hosts

2. Create the Bash Script to copy public key to remote server:

[root@linuxtutors# ~]# vi autossh.sh

#!/bin/bash

ips=/tmp/List_Of_Machine_IPs.txt

for x  in $(cat $ips)

do

cat .ssh/id_rsa.pub | ssh root@$x 'cat >> .ssh/authorized_keys'

cat .ssh/id_rsa.pub | ssh root@$x 'cat >> .ssh/authorized_keys2'

ssh root@$x 'chmod 640 .ssh/authorized_keys'

ssh root@$x 'chmod 640 .ssh/authorized_keys2'

ssh root@$x 'chmod 700 .ssh'

done

Save and Exit:

:wq

3. Assign the execute permission to the script:

[root@linuxtutors# ~]# chmod a+x autossh.sh

4. List all the machine ip which you want to autologin:

[root@linuxtutors# ~]# vi /tmp/List_Of_Machine_IPs.txt

192.168.1.100

192.168.1.101

192.168.1.102

Save and Exit:

:wq

5. Execute the script

[root@linuxtutors# ~]# sh autossh.sh

The authenticity of host '192.168.1.100 (192.168.1.100)' can't be established.

RSA key fingerprint is ae:14:11:0f:cc:2a:28:03:b4:13:7f:35:ce:ab:f5:ee.

Are you sure you want to continue connecting (yes/no)? yes

Warning: Permanently added '192.168.1.100' (RSA) to the list of known hosts.

root@192.168.1.100's password:

root@192.168.1.100's password:

The authenticity of host '192.168.1.101 (192.168.1.101)' can't be established.

RSA key fingerprint is ae:14:11:0f:cc:2a:28:03:b4:13:7f:35:ce:ab:f5:ee.

Are you sure you want to continue connecting (yes/no)? yes

Warning: Permanently added '192.168.1.101' (RSA) to the list of known hosts.

root@192.168.1.101's password:

root@192.168.1.101's password:

The authenticity of host '192.168.1.102 (192.168.1.102)' can't be established.

RSA key fingerprint is ae:14:11:0f:cc:2a:28:03:b4:13:7f:35:ce:ab:f5:ee.

Are you sure you want to continue connecting (yes/no)? yes

Warning: Permanently added '192.168.1.102' (RSA) to the list of known hosts.

root@192.168.1.102's password:

root@192.168.1.102's password:

[root@linuxtutors# ~]#