This is my first document on this forum and it will help you in configuring ssh keys for autologin.
Scope:
This document will guide you in configuring ssh keys on Linux, normally you need such type of configuration when you connect to some Linux server using some scripts without giving username and password to do some sys admin activity.
Steps:
Make sure that ssh is installed on all the servers. Here is the output of rpm -qa from server1
Code:
[root@server1 ~]# rpm -qa |grep ssh
openssh-clients-3.9p1-8.RHEL4.9
openssh-askpass-3.9p1-8.RHEL4.9
openssh-3.9p1-8.RHEL4.9
openssh-server-3.9p1-8.RHEL4.9
openssh-askpass-gnome-3.9p1-8.RHEL4.9
[root@server1 ~]#[/i]
Here is the output of rpm -qa from server2
Code:
[root@server2 ~]# rpm -qa | grep ssh
openssh-clients-3.9p1-8.RHEL4.9
openssh-askpass-3.9p1-8.RHEL4.9
openssh-3.9p1-8.RHEL4.9
openssh-server-3.9p1-8.RHEL4.9
openssh-askpass-gnome-3.9p1-8.RHEL4.9
[root@server2 ~]#
Now generate a ssh key on server1 using following commands.
Code:
[root@server1 ~]# ssh-keygen -t dsa (Press Enter)
Generating public/private dsa key pair.
Enter file in which to save the key (/root/.ssh/id_dsa):
Enter passphrase (empty for no passphrase): (Enter passphrase if you want, otherwise just Enter)
Enter same passphrase again: (Enter Again)
Your identification has been saved in /root/.ssh/id_dsa.
Your public key has been saved in /root/.ssh/id_dsa.pub.
The key fingerprint is:
1e:56:19:54:86:03:38:61:d5:1e:2c:c7:c3:11:bf:50 root@server1
[root@server1 ~]#
Now you need to copy /root/.ssh/id_dsa.pub from server1 to server2 and need to rename it to authorized_keys, place this file in the same directory i.e. /root/.ssh on server2. If you don't find this directory then create it and chnage the permissions to 644 using chmod.
Code:
[root@server1 ~]# scp /root/.ssh/id_dsa.pub server2:/root/.ssh/authorized_keys
The authenticity of host 'server2 (10.216.152.221)' can't be established.
RSA key fingerprint is c1:14:0b:ef:0d:c7:48:94:2e:e3:fc:62:9a:2c:e6:2b.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'server2' (RSA) to the list of known hosts.
root@server2's password:
id_dsa.pub 100% 602 0.6KB/s 00:00
Note: Here you need to give root password of server2 since you are scping the file with username root from server1. Once you have configured ssh keys it wont ask you about the password.
Now login to server2 and check for authorized_keys file in /root/.ssh directory.
Code:
[root@server2 .ssh]# pwd
/root/.ssh
[root@server2 .ssh]# ls -lrt
total 24
-rw-r--r-- 1 root root 224 Jan 27 06:22 known_hosts
-rw-r--r-- 1 root root 602 Jun 14 05:54 id_dsa.pub
-rw-r--r-- 1 root root 602 Jun 14 07:28 authorized_keys
[root@server2 .ssh]#
Now login from server1 to server2 using ssh and it will not ask for any password.
Code:
[root@server1 ~]# ssh server2
Last login: Wed Jun 14 07:28:36 2006 from server2
[root@server2 ~]#
To achive the same from server2, follow the all steps mentioned above on server2.
Do let me know your comments on this document.
Thanks for your reading!