Mac Dnsmasq搭建DNS服务

转载： https://passingcuriosity.com/2013/dnsmasq-dev-osx/
Most web developers will be familiar with the process of updating your

/etc/hosts

file to
direct traffic for

coolproject.dev

to

127.0.0.1

.
Most will also be familiar with the problems of this approach:

it requires a configuration change every time you add or remove a project; and

it requires administration access to make the change.

Installing a local DNS server like Dnsmasq and configuring your system to use that server
can make these configuration changes a thing of the past. In this post, I’ll run through the process of:

Installing Dnsmasq on OS X.

Configuring Dnsmasq to respond to all

.dev

requests
with

127.0.0.1

.

Configure OS X to send all

.dev

requests
requests to Dnsmasq.

Before we get started, I should give you a warning: these instructions show you how to install new system software and change your system configuration. Like all such changes, you should not proceed unless you are confident you have understood
them and that you can reverse the changes if needed.

Installing Dnsmasq

To quote the Dnsmasq project home page

Dnsmasq is a lightweight, easy to configure DNS forwarder and DHCP server […] is targeted at home networks[.]

There are plenty of ways to install Dnsmasq but my favourite (on OS X) is to use the Homebrew package manager. Installing Homebrew is fairly
simple but beyond my scope here.

Once you have Homebrew installed, using it to install Dnsmasq is easy:

# Update your homebrew installation
brew up
# Install dnsmasq
brew install dnsmasq

The installation process will output several commands that you can use to start Dnsmasq automatically with a default configuration. I used the following commands but you should use whichever commands

brew

tells
you to:

# Copy the default configuration file.
cp $(brew list dnsmasq | grep /dnsmasq.conf.example$) /usr/local/etc/dnsmasq.conf
# Copy the daemon configuration file into place.
sudo cp $(brew list dnsmasq | grep /homebrew.mxcl.dnsmasq.plist$) /Library/LaunchDaemons/
# Start Dnsmasq automatically.
sudo launchctl load /Library/LaunchDaemons/homebrew.mxcl.dnsmasq.plist

Configuring Dnsmasq

Now that you have Dnsmasq installed and running, it’s time to configure it! The configuration file lives at

/usr/local/etc/dnsmasq.conf

by
default, so open this file in your favourite editor.

One the many, many things that Dnsmasq can do is compare DNS requests against a database of patterns and use these to determine the correct response. I use this functionality to match any request which ends in

.dev

and
send

127.0.0.1

in response. The Dnsmasq configuration directive to do this is very simple:

address=/dev/127.0.0.1

Insert this into your

/usr/local/etc/dnsmasq.conf

file (I put it near the example

address=/double-click.net/127.0.0.1

entry
just to keep them all together) and save the file.

You may need to restart Dnsmasq to get it to recognise this change. Restarting Dnsmasq is the same as any other service running under

launchd

:

sudo launchctl stop homebrew.mxcl.dnsmasq
sudo launchctl start homebrew.mxcl.dnsmasq

You can test Dnsmasq by sending it a DNS query using the

dig

utility. Pick a name ending
in

dev

and use dig to query your new DNS server:

dig testing.testing.one.two.three.dev @127.0.0.1

You should get back a response something like:

;; ANSWER SECTION:
testing.testing.one.two.three.dev. 0 IN	A	127.0.0.1

Configuring OS X

Now that you have a working DNS server you can configure your operating system to use it. There are two approaches to this:

Send all DNS queries to Dnsmasq.

Send only

.dev

queries
to Dnsmasq.

The first approach is easy – just change your DNS settings in System Preferences – but probably won’t work without additional changes to the Dnsmasq configuration.

The second is a bit more tricky, but not much. Most UNIX-like operating systems have a configuration file called

/etc/resolv.conf

which
controls the way DNS queries are performed, including the default server to use for DNS queries (this is the setting that gets set automatically when you connect to a network or change your DNS server/s in System Preferences).

OS X also allows you to configure additional resolvers by creating configuration files in the

/etc/resolver/

directory.
This directory probably won’t exist on your system, so your first step should be to create it:

sudo mkdir -p /etc/resolver

Now you should create a new file in this directory for each resolver you want to configure. Each resolver corresponds – roughly and for our purposes – to a top-level domain like our

dev

.
There a number of details you can configure for each resolver but I generally only bother with two:

the name of the resolver (which corresponds to the domain name to be resolved); and
the DNS server to be used.

For more information about these files, see the

resolver(5)

manual page:

man 5 resolver

Create a new file with the same name as your new top-level domain (I’m using

dev

,
recall) in the

/etc/resolver/

directory and add a

nameserver

to
it by running the following commands:

sudo tee /etc/resolver/dev >/dev/null <<EOF
nameserver 127.0.0.1
EOF

Here

dev

is the top-level domain name that I’ve configured Dnsmasq to respond to and

127.0.0.1

is
the IP address of the server to use.

Once you’ve created this file, OS X will automatically read it and you’re done!

Testing

Testing you new configuration is easy; just use

ping

check that you can now resolve some
DNS names in your new top-level domain:

# Make sure you haven't broken your DNS.
ping -c 1 www.google.com
# Check that .dev names work
ping -c 1 this.is.a.test.dev
ping -c 1 iam.the.walrus.dev

You should see results that mention the IP address in your Dnsmasq configuration like this:

PING iam.the.walrus.dev (127.0.0.1): 56 data bytes

You can now just make up new DNS names under

.dev

whenever you please. Congratulations!

Maybe the next step on your journey should be learning how to do configure Apache virtual hosts automatically based on host names? If this sounds interesting, contact me using the details below and I’ll write that article too.

关键的步骤：

在DNS，dnsmasq.conf文件中添加：address=/test.com/127.0.0.1

在相应的目录下添加 /etc/resolver/test.com，对应的内容为nameserver 127.0.0.1

sudo cp -fv /usr/local/opt/dnsmasq/*.plist /Library/LaunchDaemons

sudo chown root /Library/LaunchDaemons/homebrew.mxcl.dnsmasq.plist

sudo launchctl load /Library/LaunchDaemons/homebrew.mxcl.dnsmasq.plist

sudo launchctl stop homebrew.mxcl.dnsmasq

sudo launchctl start homebrew.mxcl.dnsmasq