Generating and installing an RSA key

Simcenter Amesim uses a key authentication method to remote HPC clusters and uses the SSH protocol to communicate. This section will guide you through the steps required to generate an RSA key pair and install the public key on your remote account for password-free secured authentication.

Installing an SSH client and key generator

Note

We recommend PuTTY as the secure shell and key generator application to generate an RSA key on a Microsoft Windows machine.

Download PuTTY installer (MSI ‘Windows Installer’) from here. Alternatively you can download putty.exe and puttygen.exe.

Figure 27: PuTTY download

Run the downloaded installer with the default settings.

Creating a private and public key pair on the local machine

Procedure

1. On the local machine go to Start > PuTTY > PuTTYgen.

2. In PuTTYgen, click on Generate and follow the instructions by moving your mouse around the blank area to generate randomness and produce an encrypted key pair.

3. Once the key is created, click on Conversions > Export OpenSSH Key and save it to a location on your local machine that you will access later.Note Do not set a passphrase as Simcenter Amesim will not ask you for it when using the private key. The exported OpenSSH private key shall remain confidential and shall not be moved or copied out of your local machine. It is important not to store your key file on a network drive or a removable medium, this file being protected by authentication to your local machine instead of a passphrase. Do not use the Save private key button which generates a key file in .ppk format not supported by Simcenter Amesim.

4. Copy all of the content of the Public key field by first clicking and dragging to highlight the content of the window and then press Ctrl+C (or right-click and Copy). Note We will place it on the remote machine such that when the local machine tries to gain access to the remote machine, access is granted without being prompted for a password. Figure 28: PuTTY Key Generator

Copying the public key to the remote machine

Procedure

1. Launch PuTTY using Start > PuTTY > PuTTY.

2. In the Host Name (or IP address) field, enter either the host name or the IP address of the remote machine, set the Port number and click Open.Note If the host name does not work, user the IP address. Figure 29: Launch PuTTY

   Note If you are logging in to the remote HPC cluster for the first time, you will be asked if you recognize its fingerprint. Check with your IT department if the displayed fingerprint matches expectations for the HPC cluster you are trying to connect to. If, and only if it matches, click on Yes to connect and store the fingerprint in PuTTY’s cache, or No to connect but without storing the fingerprint in PuTTY’s cache. Figure 30: PuTTY security alert

3. Log in using the user name and password required for the remote machine account.

4. Using the text editor vi, create a temporary file to store your public key by using the command:vi pubkey.

5. Enter the interactive mode in vi using the i key. Right-click in the window. This should copy the content of the clipboard (the public key) into the vi window. The editor should look similar to the window below:Figure 31: vi window

6. Exit interactive mode by pressing the Esc key.

7. Save and quit by typing::wq

8. Append the content of the temporary file to your authorized keys file and remove the temporary file by using the commands:cat pubkey >> .ssh/authorized_keys rm –f pubkey

9. Close the PuTTY session by issuing the command:exit

10. Close the PuTTY Key Generator.