Puttygen SSH2 rsa

You get a putty command package (putty.zip) (and a terminfo of putty) and extract to the suitable directory.

Preparation

If you have ssh2 public keys, private keys, and authorized_keys[2] (concatenated file of some kind of public keys), gather them and store to a directory. You must not locate this directory in the My Document or shared directories if you want to avoid the threat of viruses.

Translate OpenSSH private key to PuTTY private key using puttygen

PuTTY does not accept the OpenSSH private key itself.
You need to convert the format of the OpenSSH private key to the PuTTY private key (.PPK) using puttygen.exe.
(Putyugen.exe can generate public/private key pair also. )

When you execute puttygen.exe, it shows following window.

Load the OpenSSH (ssh2) private key by the action of "Load an existing private key file". The location of loading key is set to . The input request of passphrase is executed just after loading the OpenSSH private key. When it passes passphrase authentication, it displays following window.

Key comment is displayed just before the passphrase input prompt in the ssh login sequence. Change the comment string if you need.

Save the PuTTY private key file (.PPK) by the [Save private key] button in the "Save the generated key" action.

In the help document of puttygen, ssh2-rsa is recommended against ssh2-dsa.

PuTTY Configuration

You can see the following PuTTY Configuration window first when you execute putty.exe.

Connection-Data to send to the server: You can select PuTTY as terminal type if you install the putty terminfo (putty.info) to your host.

Connection-SSH:
Data to send to the server: Write the remote command name into the box if you want the remote command execution.
Protocol options-Enable compression: Check the box if you want to do the thin band-width communication by data compression.
Preferred SSH protocol version: Select "2" or "2 only".

Connection-SSH-Auth-Private key file for authentication:
Select the PuTTY private key file (.PPK) which is generated from the OpenSSH private key by

Session-Basic options for your PuTTY session:
Host name, Protocol
Saved sessions: Save the configuration of each session.
Default Settings does not contain the host name.
If you want to save the host name, you must save the session by the name of other than "Default Settings".

SSH login using PuTTY

After executing putty.exe, loading a saved session and pushing a open button starts the ssh session.

It shows the "login as:" prompt when you stay blank the box of auto login user name at in the PuTTY configuration, In such case, you input your login name following to the prompt.

You input your ssh passphrase against the prompt of passphrase request and it passes the ssh authentication, your login session begins.