Connecting via SSH on Unix¶

Activating your Key in the SSH Key Agent¶

Note

The big Linux distributions automatically manage ssh-agent for you and unlock your keys at login time. If this doesn't work for you, read on.

ssh-agent caches your SSH keys so that you do not need to type your passphrase every time it is used. Activate it by making sure ssh-agent runs in the background and add your key:

$ eval "$(ssh-agent -s)"
$ ssh-add

or if you chose a custom key name, specify the file like so:

$ ssh-add ~/.ssh/mdc_id_rsa

MacOS¶

If you run into problems that your key is not accepted when connecting from MacOS, please use:

$ ssh-add --apple-use-keychain

Configure SSH Client¶

You can define a personal SSH configuration file to make connecting to the cluster more comfortable by reducing the typing necessary by a lot. Add the following lines to the file ~/.ssh/config file. Replace USER_NAME with your cluster user name. You can also adapt the Host naming as you like.

Host bihcluster
    HostName hpc-login-1.cubi.bihealth.org
    User USER_NAME

Host bihcluster2
    HostName hpc-login-1.cubi.bihealth.org
    User USER_NAME

Now, you can do type the following (and you don't have to remember the host name of the login node any more).

$ ssh bihcluster

This configuration works if you are inside Charité, the Charité VPN, or MDC.

MDC users: Jail node¶

If you have an MDC user account and want to connect from the outside, you can use the following ~/.ssh/config lines to set up a ProxyJump via the MDC SSH jail.

Host mdcjail
    HostName ssh1.mdc-berlin.de
    User MDC_USER_NAME

Now you can run

$ ssh -J mdcjail bihcluster1

If you are always connecting from outside the internal network, you can also add a permanent ProxyJump to the SSH configuration like so:

Host bihcluster
    HostName hpc-login-1.cubi.bihealth.org
    User USER_NAME
    ProxyJump mdcjail

Connecting with another computer/laptop¶

If you need to connect to the cluster from another computer than the one that contains the SSH keys that you submitted for the cluster login, you have two possibilities.

Generate another SSH key pair and submit the public part as described beforehand.
Copy your private part of the SSH key (~/.ssh/id_rsa) to the second computer into the same location.

Danger

Do not leave the key on any USB stick. Delete it after file transfer. This is a sensible part of data. Make sure that the files are only readable for you.

$ cd ~/.ssh
$ chmod g-rwx id_rsa*
$ ssh-add  id_rsa

File System mount via sshfs¶

$ sshfs <USERNAME>@hpc-transfer-1.cubi.bihealth.org:/ <MOUNTPOINT>

hpc-transfer-1: follows the structure <host>:<directory> starting in the user home.
<MOUNTPOINT> must be an empty but existing and readable directory on your local computer

MacOS¶

Make sure you have both OSXFUSE and SSHFS installed. You can get both from here: https://osxfuse.github.io/ or the most recent version via Homebrew:

$ brew cask install osxfuse; brew install sshfs; brew link --overwrite sshfs

The last command is optional and unlinks any pre-existing links to older versions of sshfs. Now you can run

$ sshfs -o follow_symlinks <USERNAME>@hpc-transfer-1<X>.cubi.bihealth.org:<directory_relative_to_Cluster_root> <MOUNTPOINT> -o volname=<BIH-FOLDER> -o allow_other,noapplexattr,noappledouble

X11¶

Do you really need to run a graphical application on the cluster?

Please note that running more complex Java applications, such as IGV may be not very efficient because of the connection speed. In most cases you can run them on your local workstation by mounting them via SSHFS.

Connect to one of the login nodes using X11 forwarding:

$ ssh -X -C -t <USERNAME>@hpc-login-1.bihealth.org

Once you get a login prompt, you can use the srun command with the --x11 parameter to open a X11 session to a cluster node:

$ srun --pty --x11 bash

And finally you can start your X11 application, e.g.:

$ xterm

After a while Visual Terminal should start: