Category: dns

Git pre-commit hook for DNS zone data

If you’re storing your DNS configuration in Git, a pre-commit hook to automatically run named-checkzone before zone file changes are committed may be useful to you. The pre-commit hook I use assumes that zone files (and only zone files) are in the format db.<zonename> (e.g. “db.andyleonard.com”), and only tests zone files (e.g. named-checkconf is not run against configuration files).

This pre-commit hook’s structure is based heavily on a Puppet 2.7 pre-commit published elsewhere. Continue reading

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Git-driven BIND (plus Fabric)

Step 0. Store your DNS configuration in Git. If you aren’t using some sort of version control system for your zone files and other BIND configuration, you ought to be. May I recommend Git? Put your entire configuration directory in there, but do read the “Downsides” section below for some important security considerations.

Step 1. Create a bare Git repository on your DNS server. Using Fabric, you’d do it something like this:

def config_git():

    # Create bare git repo for direct DNS data pushes:
    sudo('/bin/mkdir /srv/bind.git')
    sudo('/bin/chown ubuntu:ubuntu /srv/bind.git')
    with cd('/srv/bind.git'):
        run('/usr/bin/git init --bare .')
    git_post_receive()

(The above assumes an Ubuntu system, where the “ubuntu” user has sudo privileges, such as on EC2; adjust to your environment as needed.)
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What’s Wrong With OpenDNS

First off, before I get to anything that’s wrong, there’s a lot that’s right about OpenDNS: It’s a simple, effective and flexible tool for content filtering. As a company, they’re trying to improve the state of DNS for end users with tools like DNSCrypt. You can’t beat their entry-level price – free. Their anycast network is good, especially if you’re on the west coast of the United States, like I am (in fact, it’s better for me than surely-much-larger Google’s 8.8.8.8 and 8.8.4.4). Their dashboard is pretty neat, too.

Second, let’s get the most common complaint about OpenDNS – one that isn’t going to be discussed here any further – out of the way: Their practice of returning ads on blocked or non-existent sites in your browser, via a bogus A RR of 67.215.65.132 (if you don’t go with one of their paid options). OpenDNS is upfront about doing this, so you can decide if the trade-off is worthwhile before you sign up – and you can quit using them any time you want.

Those two preliminaries covered, here’s a case study of what I think is a serious problem with OpenDNS, plus some thoughts on how they could fix it.
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