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>Two hosts on the same subnet can reach each other without leaving the LAN. Barring "very buggy software," when is this false?
by StilesCrisis 1mo ago
>Two hosts on the same subnet can reach each other without leaving the LAN.
Barring "very buggy software," when is this false?
- Waterluvian 1mo agoYeah… I feel like “falsehoods X believe about Y” need to omit anything a reasonable X would consider to be a bug. Edit: fair point. Maybe not.
- basilikum 1mo agoVPNs
- alanwreath 1mo agoI read that like the meme: <guy with messy hair>Aliens</guy with messy hair>
- dipierro 1mo agoPort- or Client-isolation on Ethernet switches and Wi-Fi access points respectively. Often seen in corporate environments and (properly configured) guest networks.
- StilesCrisis 1mo agoI feel like the point of those is conceptually "take these things off the LAN." If we allow for that, what even is a LAN?
- mitxela 1mo agoYou are correct. It explicitly breaks the LAN, does not provide a LAN, only an internet gateway in most cases.
- justinlivi 1mo agoI feel like the better of this is maybe "will" instead of "can"
- rcxdude 1mo agoSwitches and firewalls can do all kinds of things. Probably the most common case is that public/guest wifi networks often have client isolation set up so that different devices on the network can't contact each other. Same subnet, but only access to the gateway and the internet in practice. (Also can happen if ARP is not working correctly, which can be a right PITA to debug).
- Hikikomori 1mo agoSome tunnel that extends the subnet somewhere else. Guess it depends on how you define lan.
- wmf 1mo agoThere are recent "client isolation" features that prevent P2P communication. Some hosting providers also block customers on the same LAN from attacking each other.
- jrockway 1mo agoIndeed. You might share a subnet with other customers of your ISP, but your ISP probably doesn't let you ARP poison them. This isn't even that recent. I remember doing ARP poisoning exactly once and then being surprised that it didn't work everywhere.
- jrockway 1mo agoIndeed. You might share a subnet with other customers of your ISP, but your ISP probably doesn't let you ARP poison them. This isn't even that recent. I remember doing ARP poisoning exactly once and then being surprised that it didn't work everywhere. I think the falsehood here is that same IPv4 subnet = same link layer network, but that doesn't have to be the case.
- Hikikomori 1mo agoDid arp poisoning in school and used a tool to show images from websites people visited on the projector. Teacher thought it was fun until someone went to goatse.
- mitxela 1mo agoLAN spread across sites with a WAN in the middle of it. But that's why I said in my comment that a LAN isn't actually a real thing.
- taneq 1mo agoMost consumer wifi routers I’ve used have a setting to prevent peer-to-peer traffic. Whether this still counts as being on the same subnet is kind of a philosophical question.