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===== FILE: 04_Magus02_SSH.txt =====
PASTE INTO WIKI PAGE: Magus02/SSH

{{DISPLAYTITLE:SSH Access — Magus02 HPC}}
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📍 [[Magus02/Knowledge_Base|Magus02 Knowledge Base]] → Basics → SSH Access
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SSH (Secure Shell) is the standard protocol for accessing Magus02. It provides encrypted command-line access to the cluster's login nodes.

__TOC__

== General ==

SSH allows you to log into a remote computer over a network and execute commands as if you were physically present. On Magus02, SSH connects you to the '''login nodes''' — dedicated front-end machines from which you can compile code, manage files, and submit jobs to Slurm.

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⚠️ <strong>Important:</strong> Access to Magus02 login nodes is restricted to the SNU campus network. If you are off-campus, you must first connect to the SNU VPN before SSH will work. See the <strong>External Access</strong> section below.
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== SSH Clients by Platform ==

=== Linux / macOS ===

OpenSSH is pre-installed. Open a terminal and run:

<pre>
$ ssh your_username@magus02.snu.edu.in
</pre>

On first connection, you will be asked to verify the host fingerprint — type <code>yes</code> to accept. Enter your password when prompted.

To enable X11 forwarding (for graphical applications):

<pre>
$ ssh -X your_username@magus02.snu.edu.in
# If -X doesn't work, try -Y (trusted forwarding):
$ ssh -Y your_username@magus02.snu.edu.in
</pre>

=== Windows ===

Since Windows 10 version 1709, SSH is built in. Open '''Command Prompt''' or '''PowerShell''' and run:

<pre>
ssh your_username@magus02.snu.edu.in
</pre>

Alternatively, use a dedicated SSH client:

{| class="wikitable" style="width:100%;"
|-
! Client !! Notes !! Download
|-
| '''PuTTY''' || Classic, lightweight, widely documented || [https://putty.org putty.org]
|-
| '''MobaXterm''' || Integrated SSH + X11 + SFTP file browser || [https://mobaxterm.mobatek.net mobaxterm.mobatek.net]
|-
| '''Bitvise''' || Full-featured SSH + SFTP client || [https://bitvise.com bitvise.com]
|-
| '''Windows Subsystem for Linux (WSL)''' || Full Linux environment within Windows; use <code>ssh</code> natively || Built-in (enable via Windows Features)
|}

== SSH Key Authentication ==

For convenience and improved security, use SSH key pairs instead of passwords. Generate a key pair on your local machine:

<pre>
$ ssh-keygen -t ed25519 -C "your_email@snu.edu.in"
# Accept the default location (~/.ssh/id_ed25519)
# Set a strong passphrase

# Copy your public key to Magus02:
$ ssh-copy-id your_username@magus02.snu.edu.in
</pre>

After this, SSH logins no longer require typing your password each time.

== External Access — VPN ==

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<div style="font-weight:700;font-size:15px;color:#f0c040;margin-bottom:8px;">🔒 VPN Required for Off-Campus Access</div>
<div style="font-size:14px;color:#c8a850;line-height:1.7;">To access Magus02 from outside the SNU campus network, a VPN connection is mandatory. Without it, the SSH connection will time out. To obtain VPN credentials, submit a VPN Request Form to the HPC admin team or scan the QR code in your welcome email.</div>
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Once VPN is active, SSH works exactly as normal:

<pre>
# 1. Connect to SNU VPN using the provided client
# 2. Then SSH as usual:
$ ssh your_username@magus02.snu.edu.in
</pre>

== Resetting Your Password ==

; Step 1: Log in to Magus02 via SSH with your current password.
; Step 2: Run the <code>passwd</code> command:

<pre>
[user@magus02 ~]$ passwd
Changing password for user user.
Current password: ••••••••
New password: ••••••••
Retype new password: ••••••••
passwd: all authentication tokens updated successfully.
</pre>

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🔐 <strong>Password Policy:</strong> Minimum 8 characters; must include uppercase, lowercase, numbers, and special characters. Shared passwords are strictly prohibited.
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== References ==

* [https://www.freebsd.org/cgi/man.cgi?query=ssh&sektion=1 SSH man page]
* [[Magus02/Getting_Started|Getting Started on Magus02]]
* [[Magus02/File_Transfer|File Transfer (SCP / WinSCP)]]

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[[Magus02/Knowledge_Base|↑ Back to Knowledge Base]] · Maintained by HPC Administration · wiki.snu.edu.in
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