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by keeperofdakeys 3237 days ago
It seems to mostly come down to differences in how things are defined. DNS itself can handle almost arbitrary data https://tools.ietf.org/html/rfc2181#section-11, while an Internet Hostname was defined to be more strict https://tools.ietf.org/html/rfc1123#section-2. The same issue also exists with dashes at the end of domain components.

I'm not enough of a history boffin to know how Microsoft came to support it differently (perhaps something from the Netbios and NT era). At this point in time though, I don't see either party changing their default validations to agree on a single definition.

Edit: If you're curious, this is the first commit that appears to be the first glibc commit limiting dashes at the end of URLS https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=fa0bc.... I don't know about BSD libc, or windows however.
2 comments
tzs 3237 days ago
Wait a second...does this imply that if I put downloads that should only be of interest to our Windows customers on a server named something like downloads_.ourdomain.com, it might keep out all those annoying bots that ignore robots.txt and make a lot of noise in my logs? I'm guessing that most of the bots are not running on Windows.
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keeperofdakeys 3237 days ago
That's a pretty bad idea, you shouldn't rely on this kind of stuff.

If there are people running OSX or Linux that want Windows downloads, or someone is behind a captive portal or proxy (like squid), they probably won't be able to reach it anymore.

If you have a real problem with bots, I'd look at what IPs they are coming from, and how often they try to connect. Something like IP blacklisting, or fail2ban might work for your use case.

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modalduality 3237 days ago
Wow, how did you find that commit?
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keeperofdakeys 3237 days ago
Both git and this git web view allow you to view all the commits that have modified just that file. Eg. https://sourceware.org/git/?p=glibc.git;a=history;f=resolv/r.... So it's a simple matter of looking at the diffs between commits.

Of course that's assuming you know the right file, which is often the harder problem.

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