Advisory - special case TLD's and zeroconf

[sfx2000]

Not sure where else to put this, but this seems as good place as any based on active 3rd party developers and script writers...

As part of a project, we ran into an odd problem with one of our testers - one of our tasks does mDNS for service and node discovery within the local subnets - and his site was acting beyond bizarre - come to find that his particular network was resolving anything with .local as unicast DNS...

So his private DNS server (dnsmasq) was resolving .local, and not returning correct info... we got him to change over to .lan, resolving his particular problem.

.test, .local, .onion, and a few others (I've posted a comprehensive list over in the general wireless forum..)

Remember that 240.0.0.0/4 along with the 169.254.0.1 thru 169.254.255.254 ranges should be handled with care... esp. the multicast range as there are meshes that might use this for internal messaging across nodes...

 

[thelonelycoder]

In AB-Solution, I completely remove local, localhost and localhost.localdomain for this reason. I did have some weird behavior at on time. Removing these in the downloaded hosts files solved it immediately.

 

[sfx2000]

Hmm... hokay, this is perhaps relevant to Asus and other vendors...

AsusWRT does allow in their WebGUI to put a .local in the config (perhaps also .test, .onion, etc) - which isn't a good thing...

See below... (kids, don't try this at home) - not sure how to fix this upfront in an area of the WebUI that only the brave dare to tread...

@RMerlin has hinted in the past, that .local is not a good thing to use - and I concur - putting .local in particular can break Airplay and Airprint for Apple devices (and other devices that may depend on mDNS service discovery and name resolution).

I would go as far as being very careful about the normal TLD's - since stuff like .COM, .NET, etc in some contexts (like VPN or TOR) could result in some level of leakage...

 

[highwire]

Seems like a relatively common issue. My pfSense box has this warning: "Do not use 'local' as a domain name. It will cause local hosts running mDNS (avahi, bonjour, etc.) to be unable to resolve local hosts not running mDNS."

The warning is true. I used local at one point and things did not go well.

 

[john9527]

Just added a patch for my fork....
webui: prevent use of registered domain names for router domain