SSH Key generation and login:MobaXterm version

National Institutes of Natural Sciences
Okazaki Research Facilities
Research Center for Computational Science (RCCS)(Verified with MobaXterm Personal Edition v23.6)

Changelog• Jul. 16, 2019
• Feb 3, 2021
• Jan 5, 2022
• Mar 8, 2022
• Dec 20, 2022
• Jan 18, 2024

First version
Update (images, ssh key recommendation etc.)
Verified with version 21.5 and update about RSA
Updated for MobaXterm 22.0
Verified with MobaXterm 22.3
Verified with MobaXterm 23.6

Introduction
The aim of this document is to explain how to login to RCCSsupercomputer using MobaXterm.

Table of Contents• Install MobaXterm• SSH key generation• Register public key• Login• Tips

Install MobaXterm
MobaXterm can be downloaded from the following site:
https://mobaxterm.mobatek.net/
Please install it according to the instruction.
• Both of Home Edition & Professional Edition have SSH capability.
• We use Portable version of Home Edition in this guide.
(Installer version would also work correctly.)

SSH key generation (1)Launch MobaXterm and select “MobaKeyGen” in “Tools” menu.

If you have PuTTY session
settings, they will be
automatically loaded.
(maybe read from registry)
You can use this setting if
these settings work finewith PuTTY.

Choose “MobaKeyGen”

SSH key generation (2)Choose key type and then click “Generate” button.

Click to generate key (after
clicking button, move mouse
cursor around for a while)* Old versions of MobaXterm do notsupport new RSA SHA2 algorithms(rsa-sha2-256/512).
Please use newer MobaXterm version.

Choose key typeSpecify key length- Ed25519 (check EdDSA and choose Ed25519 in the box)†Recommended - ECDSA (256, 384, or 521 bits)- RSA 4096 bits (choose RSA and input 4096 in the box)*
Key Types(If you have no preference, please try Ed25519.)†Ed448 keys won’t be accepted for now.

SSH key generation (3)Once key generation finished, new items will be shown.

RCCS recommends
passphrase of 10 ormore characters andcontaining all thefollowing 4 types ofcharacters.
- lower-case- upper-case- number- symbolThis is the public key
we need. You shouldsave this key in a file.
(Please copy whole thekey (starting from sshor ecdsa-). This window
is often too small forsome types of keys.)

Click to save theprivate key.
You might want to choose
easy-to-understandfilename such asrccs.ppk or ccfep.ppk.

- Generated private key file must be kept secret.
- OpenSSH type private key can be obtained from “Conversions” menu (if needed).
- Public key can be restored from the private key; try “Load” button.

Register Public Key
Before login, you need to register the public key.
The procedure of the public key registration is available
from the following link.
https://ccportal.ims.ac.jp/en/account/

Don’t use key from “Save public key” button of MobaKeyGen.
Key displayed at “Public key for pasting into OpenSSH...”part of MobaKeyGen window is the one what we need.

Also, the private key file must be kept secret.

Login (1)Return to the initial view and click “Session” icon.

Click thisLogin (2)Create new SSH session.
Click thisLogin (3)Input server information in the window.

Input host name “ccfep.ims.ac.jp”
Check this and input RCCS user name(three letters ID given by RCCS)
Click to open setting tab

Check this and specify private key file
Finally, click to connect

Login (4)Passphrase will be asked upon connection.

(The message depends on key type (OpenSSH or PuTTY); this sample uses PuTTY type key.)Login (5)If everything works fine, you can successfully login to RCCS.

Tips (1): X11
MobaXterm has Xserver functionality.
You can use X window application without special settings.

(If X11-forwarding item in welcome message is checked, X11 would be available.)Tips (2): verify server
MobaXterm won’t verify server upon first connection.
You can enable server verification by checking“Validate host identity at first connection” item in[Settings] menu > [Configuration].

Tips (3): SFTP
MobaXterm has SFTP function. In case of SSH connection, the red squared
region works as SFTP subsystem. You can download files using this window.

(SFTP specific session can also be created.)