ZeroDNS daemon

This is ZeroDNS daemon which provides DNS functionality on top of ZeroMQ library and NORM multicast protocol. Tested on FreeBSD only, but may work on Linux as well.

How to use it?

Quick start:

• Install ZeroMQ.
• Clone this repository into local-projects.
• Run (ql:quickload :zero-dns) in REPL.
• Run (asdf:make :zero-dns/executable). This step will build an executable file in local-projects/app/zero-dns directory.
• Allow incoming and outgoing UDP traffic to 239.192.20.1:5354 destination address.
• DNS queries will be accepted on /var/run/zero-dns/<iface_name> UNIX domain socket by default where <iface_name> is the name of that interface ZeroDNS is running on. Make sure that /var/run/zero-dns/ exists and is accessible before starting zero-dns.
• Run zero-dns -d supplying the interface which is connected to your LAN, e.g. zero-dns -d re0. The process will daemonize itself and can be killed with SIGTERM or SIGINT.

An example of name resolution query using py-zmq:

>>> import zmq
>>> ctx = zmq.Context()
>>> socket = ctx.socket (zmq.REQ)
>>> socket.connect ('ipc:///var/run/zero-dns/<iface_name>')
>>> socket.send_string ('!vonbraun.local')
>>> socket.recv()
b'192.168.20.10'
>>> socket.send_string ('~192.168.20.10')
>>> socket.recv()
b'vonbraun.local'

! is used for forward DNS lookup and ~ for reverse DNS lookup. Currently, only IPv4 is supported.

zero-dns executable supports the following options:

• -a, --address ADDRESS Multicast address and port for Zero DNS messages. Default value: 239.192.20.1:5354.
• -n, --network NETWORK Working network. Can be a network in CIDR notation or any. If the working network is specified ZeroDNS will do I/O on the interface only if the interface has an IP address belonging to that network. If this option is not specified or the working network is any ZeroDNS will always send/receive DNS messages on the interface.
• -i, --sending-interval SECONDS Interval between two ZeroDNS messages in seconds. Default value: 30.
• -t, --time-to-live SECONDS Time before ZeroDNS entry expiration in seconds. Default: 120.
• -q, --socket-directory DIRECTORY Path to a directory where UNIX domain sockets for DNS queries will be created. Default value: /var/run/zero-dns/.
• -d, --daemonize Run as a daemon.
• -h, --help Print help and exit.

Startup script for FreeBSD

If you are FreeBSD user, you can place etc/rc.d/zerodns script to /usr/local/etc/rc.d/ and etc/devd/zerodns.conf to /etc/devd/.

ZeroDNS daemon will be started as soon as some Ethernet or Wi-Fi interface is up. When this interface goes down, ZeroDNS daemon will kill itself.

Do not forget to install ZeroDNS binary to /usr/local/bin and add zerodns user.

How to use it system-wide?

To allow all programs use ZeroDNS install ZeroDNS NSS module.

Bugs & Limitations

• Has support only for IPv4.
• Can be full of undetected bugs.
• SBCL only.
• Tested on FreeBSD, but must work on other UNIX-like systems such as Linux as well.