Watch out for what you share with an LLM

The other day I was setting up a Portainer agent on my desktop PC. Portainer is software that helps you manage docker containers, so you can easily configure and deploy applications.

I have Portainer running on a server, and I wanted to use its UI to manage my applications not only on that server, but also on my desktop. For this you can start a Portainer agent on the desktop and connect to it from the main Portainer service remotely, over the local network.

Once I got the agent running on my desktop, I went to Portainer and tried to make the connection. I got an error message, so I went to a retrieval-augmented instance of Claude Sonnet 3.5 and asked for help.

It became a longer dialog, and the LLM suggested various modifications, from SELinux and firewall settings to various ways of inspecting network connectivity.

When all was failing, Claude asked me to log on to the server and do the most basic connectivity check possible: ping 192.168.68.113, using the desktop's IP in the local network. So I entered this into the Bash prompt on the server:

jogojapan@asustor:/volume1/home/jogojapan $ ping 192.168.68.113

And I got the error message below:

PING 192.168.68.113 (192.168.68.113): 56 data bytes
ping: permission denied (are you root?)

Now I was going to report the error back to Claude, so it (he?) could suggest what to try next. I could have just copy-pasted the error message, but I decided to copy-paste the entire sequence above, i.e. including the Bash prompt and the "ping" command I had entered. That wasn't necessary because Claude already knew what the command was. After all, it was Claude who had asked me to enter that command.

But I copied the whole thing just because it was easy, and I thought it couldn't hurt for Claude to see that I faithfully entered the command as advised.

Claude's answer was astonishing:

Ah, this is important context - you're trying to run this from an ASUSTOR NAS device, which has some specific restrictions. The permission denied for ping is normal on ASUSTOR devices for non-root users.
Let's try some alternative ways to verify connectivity:
[...]

Claude picked this up from my Bash prompt! When I had set up the NAS a long time before, I had chosen "asustor" as the host name, and my Bash prompt includes the host name.

I could have chosen a different host name, and a different setup for the Bash prompt. But it happened to be this, and Claude, from the word "asustor" alone, concluded that the server I was operating from was in fact an Asustor NAS.

That's very clever! And it helped us—Claude and me—to solve the connectivity issue.

Just be careful what else you might reveal to LLMs in the future. They'll pick up the hints and figure you out in no time.