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.
The reality despite what you or i might do, is that 99% of people don't carry around an ethernet or hardwire in when there is available wifi.
The library might be public, but it's still a good idea to communicate your intent or obtain permission prior to using someone else's network in away they might deem to be unexpected.
"Do you have ethernet or wired internet?" is actually a common library question and the response from whoever works the front desk will likely tell you everything you need to know.
When I entered I spoke to a different librarian about the locked PC room (due to a holiday or something). They said I could use wifi but need to give a phone number to a captive portal, which I already knew. My phone was not on me so I said: is it okay if I plug in over there by the catalog PCs? They said yes. Revealing what I mean by "plugging in”, well, i was vague for a reason. I know the population has become ethernet-hostile¹ so indeed asking for forgiveness is better than asking for permission in this situation.
¹ Another library in the area has ethernet ports but they are just decoys (dead ports). I asked the librarian what the problem is, why they are disabled, and whether we can turn them on. Librarian was helpless, and said “use wifi”, which didn’t work for me for different reasons than the other library. But the librarian basically said in so many words “not our problem.. you can just use wifi.” At another library, I was able to connect but Tor was blocked. I tried to get support from the librarian. They had no clue but were also unwilling to lead me to someone who could give support. The way it works around here is the info systems are outsourced to some unreachable tech giant, and the librarians are rendered helpless. If the SSID does not appear, the librarian can send an email to someone to say it’s down, and that’s about the full extent of their tech capability.
They’re not decoys, they’re just not patched. Because we don’t generally patch anything that’s not going to be in use. Also because some rando will probably attempt to plug their nasty ass laptop into it, which is also why we block port intrusions.
Equipment isn't free, after all, especially if you're a library.