How to use ssh without asking password?

We may need to login to other servers or our script may need to collect data from other servers. As we know, ssh is a secured connection to the remote servers and we may need to login without password. Here are the steps to use ssh login without password:

aspadmin is an existing user in both "LinuxMonitor" and "mail1" servers.

Step-1: Generating Keys:


aspadmin@LinuxMonitor:~> ssh-keygen -t rsa

Generating public/private rsa key pair.
Enter file in which to save the key (/home/aspadmin/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/aspadmin/.ssh/id_rsa.
Your public key has been saved in /home/aspadmin/.ssh/id_rsa.pub.
The key fingerprint is:
24:bf:71:70:ba:72:39:76:3e:a7:1c:bc:81:c3:92:f5 aspadmin@LinuxMonitor

Step-2: Creating ".ssh" folder in remote machine(mail1) for user(aspadmin)


aspadmin@LinuxMonitor:~> ssh aspadmin@mail1 mkdir -p .ssh

The authenticity of host 'mail1' can't be established.
RSA key fingerprint is 8b:2a:08:a9:89:8d:8e:31:25:0a:dd:77:d5:7f:30:e0.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'mail1,' (RSA) to the list of known hosts.
Password:

Step-3: Copying the key to the remote machine(mail1) for user(aspadmin)


aspadmin@LinuxMonitor:~> scp .ssh/id_rsa.pub aspadmin@mail1:~aspadmin/.ssh/authorized_keys2

Password:
id_rsa.pub 100% 231 0.2KB/s 00:00


Step-4: Thats all. Now you can connect to mail1 without password.


aspadmin@LinuxMonitor:~> ssh mail1

Last login: Wed Jun 25 14:51:52 2008 from xxx
aspadmin@mail1:~>



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Topics will be covered in this Blog are : Linux System Administrator - Memory Performance Tuning - File System - User Group - Linux / Unix Commands Processes - Virtual Swap Memory - Mail Server - Remote Access - Linux Permissions - Boot procedure system Logging - Network (xinetd) Configuration (ifconfig) - DNS - DHCP - Web Server - Kernel - Shell Script - Tuning Optimization High Availability Heart-BeatClustering-Backup and Recovery - Network Time Protocol - NIS - NFS - RPM Partition - /proc - Scheduling (crontab) - mount unmount - secured shell (ssh) - Remote Access - Virtual Network Computing (VNC) Default Ports - Services
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