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Comment by tptacek | Hacker News Reader

Nobody enables AXFR. AXFR isn't a default. I wouldn't advise someone to override that default.

If one of my clients then asked me, "because I don't enable AXFR, is wide-open-dev-machine.customer.com safer?", I would say "no, it is not".

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So you agree that disabling AXFR, if AXFR is enabled, is a good idea?

Could you explain why you think wide-open-dev-machine.customer.com is NOT safer without AXFR (assuming it blocks robots, and the web server only serves the site for "wide-open-dev-machine.customer.com")?

I'm just trying to understand how it could not be considered beneficial in any way, however much (which is what you're claiming).

I don't have to think about this much because nobody has AXFR enabled. If you had AXFR enabled, I would in fact tell you to turn it off. It isn't an operational win (unlike SSH on port 22), so what possible reason could there be for enabling it?

wide-open-dev-machine isn't safer because there's a whole variety of ways to learn about it without AXFR.

For what it's worth, I would not flag a customer for running SSH on port 22; I would certainly flag a customer for having port 22 exposed where it didn't need to be; for most SaaS/ASP-type companies, I'd flag them for having more than one SSH port exposed, and I'd recommend that they invest in a VPN instead of exposed SSH.

I think there are far more nameservers allowing AXFR than you think. Write a little app that attempts a zone transfer for the top 1000 of the Alexa list (http://s3.amazonaws.com/alexa-static/top-1m.csv.zip) and see for yourself. (Note to anyone reading: Please don't try this before you've checked if it's legal in your state/country or not.)

Could you explain how you would learn about wide-open-dev-machine as simply as by using AXFR in your scenario (you aren't on the network, so no *casting).

Edit: "so what possible reason could there be for enabling it?" is eerily similar to my message :)

Here's your answer:

    imageshack.com
    about.com
    ehow.com
    sparkstudios.com 
    yfrog.com
    liveinternet.ru
    pgmediaserve.com
    wikimedia.com
    adfly.com
    thefreedictionary.com
    amung.us
    btjunkie.com
    bluehost.com
    drtuber.com
    ero-advertising.com
    autohome.com.cn
    exblog.jp
    inetglobal.com
    milliyet.com.tr
    imagebam.com
    naukri.com
    bigpoint.com
    altervista.com
    hypergames.com
    gsmarena.com
    excite.co.jp
    admagnet.com
    macrumors.com
    linkbucks.com
    cracked.com
    traidnt.com
    radikal.ru
    paper.li
    eluniversal.com.mx
    wiktionary.org
    indianrail.gov.in
    docin.com
    123rf.com
    perezhilton.com
    mangafox.com
    hostmonster.com
    myfreecams.com
    giveawayoftheday.com
    ultimate-guitar.com
    itpro1.nikkeibp.co.jp
    pantip.com
    hawaaworld.com
    120ask.com

4.8%. That's more than I would have thought, but it's still a small number: 95.2% of the Alexa 1000 keep AXFR disabled. Also: someone should tell some of these people not to do this.

Indeed. Keep in mind it's the top, so these are the people you really expect to keep something like that hidden. I promise you the stats are much worse further down the list, or if you do the same, but for a specific country's TLD.

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