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169.254 is IPv4 link local range like IPv6 fe80 Windows will try to auto configure with a 169.254 link local if DHCP is unavailable. Not sure if anyone is actu

by nijave 3y ago

169.254 is IPv4 link local range like IPv6 fe80 Windows will try to auto configure with a 169.254 link local if DHCP is unavailable. Not sure if anyone is actually using them for LAN. They come up sometimes in point to point or for other shenanigans (commonly on cloud or virtualized networks for special services) Afaik for Firefox and Chrome you can add a trailing / to prevent it from doing a web search and attempt to do a DNS lookup instead

somerandomqaguy 3y ago
>Windows will try to auto configure with a 169.254 link local if DHCP is unavailable. Not sure if anyone is actually using them for LAN. They come up sometimes in point to point or for other shenanigans (commonly on cloud or virtualized networks for special services) I've seen it done few times for niche devices and I've done it a few times when I needed a really quick network operational and didn't want to bother setting up any supporting infrastructure such as a DHCP server. Never for any production environment though. I've toyed around with an IPv6 link local only environment but browsers don't support adding the zone identifier[1] for link local addresses. There's workarounds but in most cases for a fully isolated network it's about the same effort to setup a small DHCP server somewhere. That said it's not a comprehensive solution, Android AFAIK still won't support DHCPv6. To get that to work AFAIK requires router advertisements and some more odd finagling if privacy extensions are enabled on the device. [1]https://ungleich.ch/u/blog/ipv6-link-local-support-in-browsers/ https://ungleich.ch/u/blog/ipv6-link-local-support-in-browse...
jeroenhd 3y ago
I sure hope nobody is using 169.254 for LAN (though I suppose you could, just like you could use 100.100) but I discovered it as a pretty smart fallback for routers. I suppose you could hardcode http://[fe80::1]/ http://[fe80::1]/ on the IPv6 side as well, but I've never seen a router actually do that. The trailing slash trick sometimes worked, but not always. It took a couple of tries to get working every time I needed it to work. I bet it's some kind of problem on the mDNS layer, but regardless, the quickest way to fix it was to use an IP address. Another annoyance I have (which isn't the protocol's fault) is that on my phone I can't even hand-type IPv6 addresses because Mozilla is using some kind of regex to detect if things are URLs and that regex doesn't support IPv6. It did for a short while, but the IPv6 regex was too complex and slowed things down, so that was reverted.

by nijave 3y ago

somerandomqaguy 3y ago

>Windows will try to auto configure with a 169.254 link local if DHCP is unavailable. Not sure if anyone is actually using them for LAN. They come up sometimes in point to point or for other shenanigans (commonly on cloud or virtualized networks for special services) I've seen it done few times for niche devices and I've done it a few times when I needed a really quick network operational and didn't want to bother setting up any supporting infrastructure such as a DHCP server. Never for any production environment though. I've toyed around with an IPv6 link local only environment but browsers don't support adding the zone identifier[1] for link local addresses. There's workarounds but in most cases for a fully isolated network it's about the same effort to setup a small DHCP server somewhere. That said it's not a comprehensive solution, Android AFAIK still won't support DHCPv6. To get that to work AFAIK requires router advertisements and some more odd finagling if privacy extensions are enabled on the device. [1]https://ungleich.ch/u/blog/ipv6-link-local-support-in-browsers/ https://ungleich.ch/u/blog/ipv6-link-local-support-in-browse...

jeroenhd 3y ago

I sure hope nobody is using 169.254 for LAN (though I suppose you could, just like you could use 100.100) but I discovered it as a pretty smart fallback for routers. I suppose you could hardcode http://[fe80::1]/ http://[fe80::1]/ on the IPv6 side as well, but I've never seen a router actually do that. The trailing slash trick sometimes worked, but not always. It took a couple of tries to get working every time I needed it to work. I bet it's some kind of problem on the mDNS layer, but regardless, the quickest way to fix it was to use an IP address. Another annoyance I have (which isn't the protocol's fault) is that on my phone I can't even hand-type IPv6 addresses because Mozilla is using some kind of regex to detect if things are URLs and that regex doesn't support IPv6. It did for a short while, but the IPv6 regex was too complex and slowed things down, so that was reverted.