Putty - Password less login

Steps to generate key and access server without passwords.
Written by : Harijith R.          
Prerequisites : Download putty-0.63-installer.exe from the URL: http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html.
putty-0.63-installer.exe is a Windows installer for everything except PuTTYtel.
Step 1
Generate a public/private key pair on your local desktop. From the Start menu, run Start > All Programs > PuTTY > PuTTYgen as illustrated below.

Fig. 1 Initial PuTTYgen window.

Click the Generate button. You will be prompted to move the mouse over the blank area to generate some randomness. Do so. Shortly thereafter, the program will generate the key and display the result (see Figure 2).

Fig. 2 After keys have been generated.

click the "Save private key" button to save the private key to a file (Figure 3).

Fig. 3 Saving the private key in file mykey.ppk.
Step 2
Install the public key on the remote host to which you want to connect. Do this by pasting the public key from the Clipboard into the the authorized_keys file, which is located in the .ssh directory in your home directory on the remote host.
Step 3
Verify that public key authentication works. Basic public key authentication is enabled for a particular session in the Connection > SSH > Auth window. You must load the session profile (Figure 6) before configuring the Auth window (Figure 7).

Fig. 6 Load the appropriate session profile.

Fig. 7 Connection > SSH > Auth window.
Browse to select the saved private key which we saved in step 1 in the "Private key file for authentication" text box.
Be sure to go back to the Session window and click Save to update the profile. The session will use public key authentication as demonstrated in Figure 8.

Fig. 8 Logging in using basic public key authentication.