I plugged into ethernet (as wifi w/captive portal does not work for me). I think clearnet worked but I have no interest in that. Egress Tor traffic was blocked and so was VPN. I’m not interested in editing all my scripts and configs to use clearnet, so the library’s internet is useless to me (unless I bother to try a tor bridge).
I was packing my laptop and a librarian spotted me unplugging my ethernet cable and approached me with big wide open eyes and pannicked angry voice (as if to be addressing a child that did something naughty), and said “you can’t do that!”
I have a lot of reasons for favoring ethernet, like not carrying a mobile phone that can facilitate the SMS verify that the library’s captive portal imposes, not to mention I’m not eager to share my mobile number willy nilly. The reason I actually gave her was that that I run a free software based system and the wifi drivers or firmware are proprietary so my wifi card doesn’t work¹. She was also worried that I was stealing an ethernet cable and I had to explain that I carry an ethernet cable with me, which she struggled to believe for a moment. When I said it didn’t work, she was like “good, I’m not surprised”, or something like that.
¹ In reality, I have whatever proprietary garbage my wifi NIC needs, but have a principled objection to a service financed by public money forcing people to install and execute proprietary non-free software on their own hardware. But there’s little hope for getting through to a librarian in the situation at hand, whereby I might as well have been caught disassembling their PCs.
yeah OP needs to provide this detail specifically as it changes everything.
If the Ethernet jack was not on a desk, then it wasn't there for them to use. If they unplugged a cable to make it accessible, that is unfortunately enough to be considered tampering.
If an Ethernet jack was not expressly provided, unoccupied, at the technology access station then yes the access to Ethernet information facilities was unauthorized and illegitimate and could carry legal ramifications. Say what you want about proprietary wifi drivers, you get the access you are given and any attempts to gain further access without authorization are defined as intrusion attempts and will more likely than not be treated as such to some degree. Because honestly, the libraries aren't funded enough to have great security and Ethernet security is harder than WiFi security in practice, despite the challenges being characterized by the same principles.