The HP Color LaserJet CP3525 Printer looks like any other ordinary printer done by HP. But there’s a difference!

A friend of mine fell over this gem, and told me.

TCP/IP Settings

If you go to the machine’s TCP/IP settings using the built-in web server, the printer offers the ordinary network configure options but also one that sticks out a little exta. The “Manual cURL cURL” option! It looks like this:

I could easily confirm that this is genuine. I did this screenshot above by just googling for the string and printer model, since there appears to exist printers like this exposing their settings web server to the Internet. Hilarious!

What?

How on earth did that string end up there? Certainly there’s no relation to curl at all except for the actual name used there? Is it a sign that there’s basically no humans left at HP that understand what the individual settings on that screen are actually meant for?

Given the contents in the text field, a URL containing the letters WPAD twice, I can only presume this field is actually meant for Web Proxy Auto-Discovery. I spent some time trying to find the user manual for this printer configuration screen but failed. It would’ve been fun to find “manual cURL cURL” described in a manual! They do offer a busload of various manuals, maybe I just missed the right one.

Does it use curl?

Yes, it seems HP generally use curl at least as I found the “Open-Source Software License Agreements for HP LaserJet and ScanJet Printers” and it contains the curl license:

HP using curl for Print-Uri?

Independently, someone else recently told me about another possible HP + curl connection. This user said his HP printer makes HTTP requests using the user-agent libcurl-agent/1.0:

I haven’t managed to get this confirmed by anyone else (although the license snippet above certainly implies they use curl) and that particular user-agent string has been used everywhere for a long time, as I believe it is copied widely from the popular libcurl example getinmemory.c where I made up the user-agent and put it there already in 2004.

Credits

Frank Gevaerts tricked me into going down this rabbit hole as he told me about this string.