minor improvements

2026-07-24 11:42:50 +02:00
parent 55aef86d66
commit 6d03674b56
4 changed files with 42 additions and 11 deletions
@@ -21,15 +21,16 @@ This prompt is asking if you want to *trust* the remote system and allow the con
 This trust is guaranteed by using a special kind of SSH key called the *host key*. This key is similar
 to what is used in TLS/SSL connections, like accessing a website with an address starting with `https://...`.
 The host key uniquely identifies the remote host. Unlike TLS/SSL, which uses an intermediate arbitrator
-to validate the key (also known as a certificate authority), you as the user need to validate the the host key
+to validate the key (also known as a certificate authority), you as the user need to validate the host key
 yourself. A unique **fingerprint** is shown which you can compare to a known value (see below).

 The fingerprint is a unique hashed representation of the host key's public key. Typically the
 hashing algorithms MD5 or SHA256[^1] are used to generate this string.

-All the login nodes of the cluster have a unique *host key* which identifies the host
-and ensure that on subsequent connections are actually connecting to that host. This is
-en extra level of security to prevent man-in-the-middle and similar attacks from happening.
+All of the login nodes have a unique *host key* which identifies the host, SSH
+will always check this after the first connection to enforce that you are
+connecting to the same host. This is en extra level of security to prevent
+man-in-the-middle and similar attacks from happening.

 If you answer `yes`, the host key will be stored locally (usually in `~/.ssh/known_hosts` but
 this can be different depending on what client you are using).
@@ -52,4 +53,30 @@ host, it matches what is shown in the prompt above.*
    [Cyberduck](https://cyberduck.io/) and instead show an alternative
    fingerprint. We provide these as the `<HASH> (alt): ...` entries above.

+## Something looks wrong?
+
+If you get a prompt (or popup) that looks like:
+
+```txt
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
+@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
+IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
+Someone could be eavesdropping on you right now (man-in-the-middle attack)!
+It is also possible that a host key has just been changed.
+The fingerprint for the ED25519 key sent by the remote host is
+SHA256:nnP4IeemgKFGEVQd0WF2k7bpwQ+Xcy+XlK5iz6LZz1U.
+Please contact your system administrator.
+Add correct host key in /home/hans/.ssh/known_hosts to get rid of this message.
+Offending ED25519 key in /home/hans/.ssh/known_hosts:412
+Host key for login002.merlin7.psi.ch has changed and you have requested strict checking.
+Host key verification failed.
+```
+
+This *can* indicate that the machine you are connecting to is not the one you
+intended. If after double-checking your connection settings, you still get an
+error message, **[please contact us!](../../support/introduction.md)**
+
+Do not be tempted to modify the cached host keys (under `~/.ssh/known_hosts`)!
+
 [^1]: The hash is additionally encoded into `base64` representation.
@@ -1,4 +1,5 @@
-# ondemand.psi.ch
+# Open OnDemand @ PSI
+
 [Open OnDemand](https://www.openondemand.org/) is an open-source, web-based portal that allows researchers, students, and engineers to access High-Performance Computing (HPC) resources from any device using a web browser.

 !!! warning "Open OnDemand is currently in preview"
@@ -17,6 +18,7 @@
    see the [official Open OnDemand documentation](https://osc.github.io/ood-documentation/latest/install-ihpc-apps.html)

 ## Accessing Open OnDemand
+
 **Open Ondemand** can be accessed from your browser at <https://ondemand.psi.ch/>.

 !!! tip "Recommended browser"
@@ -1,13 +1,15 @@
 # ANSYS - CFX

-Is always recommended to check which parameters are available in CFX and adapt the below examples according to your needs.
-For that, run `cfx5solve -help` for getting a list of options.
+!!! tip
+    It is recommended to check which parameters are available in CFX and adapt
+    the below examples according to your needs.  For that, run `cfx5solve
+    -help` to get a list of options.

 ## Running CFX jobs

 ### PModules

-Is strongly recommended the use of the latest ANSYS software available in PModules.
+We strongly recommend that you use the latest version of ANSYS software available in PModules.

 ```bash
 module use unstable
@@ -18,9 +20,9 @@ module load ANSYS/2022R1

 ### Interactive: RSM from remote PSI Workstations

-Is possible to run CFX through RSM from remote PSI (Linux or Windows)
+It is possible to run CFX through RSM from remote PSI (Linux or Windows)
 Workstation having a local installation of ANSYS CFX and RSM client.  For that,
-please refer to the **[ANSYS RSM](ansys-rsm.md)** in the Merlin documentation
+please refer to the **[ANSYS RSM](ansys-rsm.md)** documentation
 for further information of how to setup a RSM client for submitting jobs to
 Merlin.

@@ -137,7 +137,7 @@ nav:
    - Jupyterhub:
      - merlin7/05-jupyterhub/jupyterhub.md
    - Open OnDemand:
-      - merlin7/06-open-ondemand/open-ondemand.md
+      - Introduction: merlin7/06-open-ondemand/open-ondemand.md
    - Software Support:
      - merlin7/07-software-support/pmodules.md
      - merlin7/07-software-support/openmpi.md