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DNS Toys (2022)

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Re: DNS Toys (2022)

#51

Post by m3047 »

ricardo81 wrote: post #26

Somewhat related, DNS lookup for (UK) business listings - same idea of 'abusing' the DNS service to provide non-DNS data. https://www.num.uk/ Though going by their roadmap, it may be they're no longer maintaining the service.

Don't use the word "abuse" unless it's in the sense of "SOAP and XHR are an 'abuse' of HTTP".

The IN (internet) class is the evolutionary "towering cedar" of the moment, but there were the CH (chaos) and HS (hesiod) classes during the cambrian period; you might review those project's purposes and goals.

Arguably the abuse today is in the form of things like ten millisecond windows for retransmission and qname minimization which optimize specifically for cloud-based web services ("happy eyeballs") at the expense of all else (and seemingly without awareness of e.g. buffer bloat). There's a whole world outside of A / AAAA resolution.

It's not unheard of to see two people with pocket protectors having a knife fight (or at least poking at each other with pencils) in the hallway at an Internet confab. "RFC" stands for "Request For Comments" and BCPs (Best Current Practice) are routinely ignored.

Re: DNS Toys (2022)

#52

Post by NoZebra120vClip »

jodrellblank wrote: post #48
NoZebra120vClip wrote: post #42

Earlier quoted context omitted.

Your reply is riddled with errors and you don't seem to actually know how the DNS protocol works at all, on the wire or otherwise. It is, firstly, impossible for "google.com" to contain a CNAME record. This would violate standards, and it's simply not done. Query or yourself; there is no CNAME at that label. Your description of how queries work is not how queries work at all. Your entire comment is a net negative and…

> " It is, firstly, impossible for "google.com" to contain a CNAME record. This would violate standards, and it's simply not done. " It is possible for an apex domain to contain/be a CNAME, and it simply is done, by many companies: https://serverfault.com/questions/55528/set-root-domain-reco...

This is a disingenuous claim, because many of the comments at the linked thread indicate that it not only is a breach of the RFC requirements, but is also liable to malfunction, so any provider/software that permits it, is going to have trouble supporting it.

I stand by what I said: it's impossible, and is simply not done [by anyone who cares about adhering to standards or interoperability.]

Re: DNS Toys (2022)

#55

Post by sevg »

koito17 wrote: post #5

This reminds me of a neat little trick I used back then to "reliably" compute IP address of my machines for a dynamic DNS utility I wrote for myself. OpenDNS resolvers (such as resolver1.opendns.com) will resolve myip.opendns.com to your actual IP address. Whether you get A or AAAA records depends on your connection. Since the IP addresses for these resolvers tend to be anycast IPs, I also want to believe they are ma…

You have a good point that most of those HTTP services out there for getting your IP don't seem like they would be particularly reliable in terms of uptime.

Worth noting that Cloudflare run one though, and that seems more likely to be reliable:

https://icanhazip.com/

https://ipv4.icanhazip.com/

https://ipv6.icanhazip.com/

Re: DNS Toys (2022)

#57

Post by piperswe »

lowpro wrote: post #38
drones wrote: post #34

(Drawing from 1-semester CCNA course in uni) Since DNS operates over UDP, isn't the amount of data that can be safely transferred effectively bottlenecked by the smallest page size between the routers that reach your device? DNS is served in one chunk, right?

Usually if a response is greater than 512 bytes the DNS server will renegotiate on TCP 53. Note some DNS servers might not do this, but every normal implementation does that I’m aware of.

Historically musl libc didn't support TCP DNS, but even musl supports it now [1]

[1]: https://www.theregister.com/2023/05/16/alpine_linux_318/

Re: DNS Toys (2022)

#58

Post by johnhenry »

rochak wrote: post #44
johnhenry wrote: post #39

I'm a big fan of Julia Evans[1] who's made a number of useful toys including ones for DNS here[2] and here[3]. - [1] https://jvns.ca/ - [2] https://dns-lookup.jvns.ca/ - [3] https://messwithdns.net/

Thanks for sharing these absolute gems!

You're welcome! I should have linked directly to the tool page: https://jvns.ca/categories/playgrounds/

Re: DNS Toys (2022)

#59

Post by ricardo81 »

m3047 wrote: post #51
ricardo81 wrote: post #26

Somewhat related, DNS lookup for (UK) business listings - same idea of 'abusing' the DNS service to provide non-DNS data. https://www.num.uk/ Though going by their roadmap, it may be they're no longer maintaining the service.

Don't use the word "abuse" unless it's in the sense of "SOAP and XHR are an 'abuse' of HTTP". The IN (internet) class is the evolutionary "towering cedar" of the moment, but there were the CH (chaos) and HS (hesiod) classes during the cambrian period; you might review those project's purposes and goals. Arguably the abuse today is in the form of things like ten millisecond windows for retransmission and qname minimiz…

Fair point. Probably showing my lack of experience previous to the millennium, at most it was debugging res_mkquery for hours because of what I was passing as a class, iirc C_ANY rather than C_IN.
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