How to connect via SSH from Windows with PuTTy and PuTTygen

The first thing you need to do is download PuTTygen to generate your private key and add it to .ssh/authorized_keys.

Once you have downloaded and started the program, you will see the following screen, where you can generate the private key:

Generate the private key as follows:

The string generated in this example is as follows:

ssh-rsa 
AAAAB3NzaC1yc2EAAAABJQAAAIBnERhIC5eDep7EYChfc6ENBX++mZzD3hjEeJrIV5sbIr9rpPkU0
VETXUyTMB59hAU1+U8tRBbvGQFoSH/5iallYKXAQmqMRyDAQw+BJ8BVGV8Ko2Ng2VZZ6p1I/DB
wMfhwMLv/uNfspwlCn2/G0GWy4zvv7VdSRp5jutrBEJMtGw== rsa-key-20130327

Once you have generated it, you must specify the private key on your Linux server in the file .ssh/authorized_keys

For security, you must set secure permissions, such as 0400. The .ssh directory should have permissions of 0700, for example. As follows:

# mkdir -p $HOME/.ssh
# chmod 0700 $HOME/.ssh
# touch $HOME/.ssh/authorized_keys
# chmod 0600 $HOME/.ssh/authorized_keys

Once you have created the directory and file, you will need to add the string generated in the previous steps.

You can then connect to the server through PuTTy with your private key using Pageant.

Pageant is a program for Windows that provides temporary access to your private key. Programs such as PuTTy or WinSCP use Pageant to securely use the generated private key.

Pageant lets you load a private key by prompting for the password and also provides indirect access to other programs through PuTTy to establish SSH connections with your private key.