SSH access

SSH is the standard way to log in to institute servers – secure, scriptable and cross-platform.

Standard · HU account

$ ssh HU-Account@ssh.mathematik.hu-berlin.de

For everyone working with their HU account – this is the standard case.

Legacy maths account only

$ ssh alter-mathe-account@math@ssh.mathematik.hu-berlin.de

The @math suffix selects the legacy maths authentication. Only needed if your account was not created at CMS.

Which account is mine? Students and staff who joined from roughly 2018 onwards use the HU account (variant 1). The legacy maths accounts (variant 2) remain functional, but no new maths accounts are being issued. In the future, the @math.hu-berlin.de email address will also be available for HU accounts – at the moment it only works for holders of legacy maths accounts.

Off-campus: A VPN connection is required. On campus (Wi-Fi eduroam, LAN) SSH is reachable directly.

Please do not run compute-intensive programs (e.g. Matlab, simulations) on the login server – use the compute servers instead.

01 · Setup

By operating system

SSH is built in on all three platforms today – no extra client needed.

Linux

Open a terminal and connect:

$ ssh yourusername@ssh.mathematik.hu-berlin.de

macOS

Open Terminal via Spotlight: ⌘ Space, type „Terminal“.

$ ssh yourusername@ssh.mathematik.hu-berlin.de

Windows 10 / 11

Open PowerShell or Command Prompt (SSH is built in since Windows 10 1809):

> ssh yourusername@ssh.mathematik.hu-berlin.de

GUI alternatives: PuTTY · WinSCP

02 · Keys Recommended

SSH keys instead of password

More secure than password login and avoids repeated prompts – set up once, then never again.

Generate a key pair (local, one-time)
```
$ ssh-keygen -t ed25519 -C "HU Berlin"
```
Accept the default path; setting a passphrase is recommended.
Upload the public key to the server
```
$ ssh-copy-id yourusername@ssh.mathematik.hu-berlin.de
```
Log in with the password once – from then on the key is enough.

Log in without a password

$ ssh yourusername@ssh.mathematik.hu-berlin.de

03 · Convenience

SSH-Konfigurationsdatei (~/.ssh/config)

Avoids retyping long hostnames over and over.

Create or extend ~/.ssh/config:

Host mathlogin
    HostName  ssh.mathematik.hu-berlin.de
    User      yourusername

Host beta
    HostName  beta
    User      yourusername
    ProxyJump mathlogin

After this:

$ ssh mathlogin           # Login-Server
$ ssh beta                # direkt auf den Rechenserver

04 · Compute servers

Connecting to compute servers

Five dedicated servers for compute-intensive tasks.

Server	Cores	CPU
`alpha`	160	Intel® Xeon® Platinum 8380 @ 2.30 GHz
`beta`	104	Intel® Xeon® Platinum 8270 @ 2.70 GHz
`eta`	224	Intel® Xeon® Platinum 8280L @ 2.70 GHz
`zeta`	224	Intel® Xeon® Platinum 8280L @ 2.70 GHz
`theta`	32	Intel® Xeon® Gold 5222 @ 3.80 GHz

Direct connection via the login server (jump host, one step):

$ ssh -J ssh.mathematik.hu-berlin.de yourusername@beta

Or in two steps:

$ ssh yourusername@ssh.mathematik.hu-berlin.de
$ ssh beta

Keeping sessions alive (tmux / screen)

Terminal multiplexers prevent running processes from being killed when the SSH connection drops (network issues, closed laptop, etc.).

Action	tmux	screen
New session	`tmux new -s name`	`screen -S name`
Detach	`Ctrl`+`b`, then `d`	`Ctrl`+`a`, then `d`
Reattach	`tmux attach -t name`	`screen -d -R name`
List sessions	`tmux ls`	`screen -ls`

05 · Files

Transferring files

Four tools – pick by scope and comfort.

rsync

Recommended for directories: transfers only changes, with progress.

$ rsync -avz local/ yourusername@ssh.mathematik.hu-berlin.de:target/
$ rsync -avz yourusername@ssh.mathematik.hu-berlin.de:source/ local/

scp

Simple for individual files.

$ scp file yourusername@ssh.mathematik.hu-berlin.de:target/
$ scp yourusername@ssh.mathematik.hu-berlin.de:source.pdf .

sshfs

Mount your home directory locally – like a USB stick.

$ sshfs yourusername@ssh.mathematik.hu-berlin.de: ~/uni_home
$ fusermount -u ~/uni_home

Graphical tools

Drag & drop, no command line.

Dolphin / Nautilus: sftp://yourusername@ssh.mathematik.hu-berlin.de/
WinSCP: winscp.net (SFTP)
Cyberduck: free for macOS / Windows