-- Purpose
This software is designed to be installed in a single location on a network where mDNS is expected to be used; multiple installations are not supported.
Note that you should definitely be trying to avoid using .local as your "intranet" domain name if you can help it - this kind of software is just for those of us unlucky enough to already have a .local domain name and no easy way to back out of that.
You can use the mDNS Unicast Lookup tool to provide a way for clients that use multicast DNS (mDNS) for local lookups instead of unicast DNS. For example, on a Windows network with a .local domain name, a Mac will attempt to perform all lookups via mDNS first, and then only try unicast DNS upon timing out. This in particular causes all manner of problems with Active Directory and other common Windows network features.
So that's where this tool comes in - any of those .local lookups via mDNS will be converted into a unicast DNS lookup, and then the result will be sent right back to the original client (via an mDNS response, no less).
This tool also shows just how insecure the current implementation of mDNS is. If any single machine on the network can intercept multicast DNS packets and send out a crafted response, services can be redirected to just about anywhere.
-- Pre-requisites
You'll need a relatively sane version of Python - really anything past 2.4 will do the trick. Python 3.x has not been tested yet.
You'll also need two libraries: DNSPython (http://www.dnspython.org), and dnslib (http://pypi.python.org/pypi/dnslib)
Download the archives, extract them, and run python setup.py install as root and you'll be good to go.
-- Installation
No installation required - the tool is standalone and will run from any directory. Just make sure proxy.py is +x (executable).
-- Usage
Just ./proxy.py.
No command-line options, no user interface of any sort - this is all meant to be something you just plug in and forget about. I'd recommend running the tool in a screen session somewhere so you can check it out quickly and easily, but how you keep it running is up to you.
If you want to try out the proxy and test that it works, the mdns-lookup.py tool is available. For example, if you wanted to get an A record for "host.local", you would simply run:
./mdns-lookup.py host.local
Or, if you wanted to find a TXT record for a name:
./mdns-lookup.py --type TXT name.local
To kill the tool, just hit CTRL-C.