[Karrot_Kream]

> Allegedly, he once removed an IPv4 address by mistake from one student's computer. He only heard about it half a year later, when the student casually mentioned that only Google, Facebook and other big sites seem to work. Apparently, if Google, Facebook, and the School's website works, it's acceptable to most (which is sad for different reasons, but that's not my point).

The fact that the "sad part" is that the student only uses big tech websites and not that this netop was able to do something like this with no alerting or guardrails says a lot about HN's culture these days.

In general I wonder what kind of alerting these dorm ISPs run. Do they ever do reachability tests for devices on their network?

[posguy]

Some university networks are run tightly, others are rather loose when it comes to security, monitoring and debugging network cables that are syncing up at lower speeds. Really depends on who is staffing the IT team...

Many older universities give you a public IPv4 address with no NAT when you plug into a network port.

OP, one neat thing you should try is broadcasting a /25 through /29 and seeing which ISPs this is routable from (eg: Lumen (aka Centurylink/Quantum), Verizon, T-Mobile, AT&T, Comcast, etc). There are a number of blocks smaller than /24's being broadcast, and it would be quite interesting to see which ISPs are willing to route traffic to smaller blocks.

[kdklol]

There's a management system that assigns IPs automatically, written in-house in the late 2000s, but yes, anything there can be manually overridden. He was probably diagnosing something earlier and forgot to clean up. Meanwhile, new students moved in I guess.

Missing IPv4 addresses are not reported as some systems are left IPv6-only intentionally. It's a dorm network, but it's sort-of a research project at the same time. It is also run by students themselves (there's a "student's union") and the school does not pay or maintain the dorm's infrastructure.

I know alerting is done for some things, but not for the individual student's machine. This is different for every dorm, but in this case, a wired symmetrical gigabit connection is provided to every member student, public IPv4 and IPv6 included. The only restriction is to not download torrents, besides that, pretty much anything can be arranged, including opening port 25, routing additional IPv6 prefixes, hosting...

It's a very free environment is what I'm getting at.