mDNS Reflector (mdns-reflector) is a lightweight and performant multicast DNS (mDNS) reflector with a modern design. It reflects mDNS queries and responses among multiple LANs, which allows you to run untrusted IoT devices in a separate LAN but those devices can still be discovered in other LANs.
- Low footprint, no dynamic memory allocation during reflecting
- Rootless - can be run as either root or non-root
- Supports zone based reflection
- Supports both IPv4 and IPv6
- Leverages epoll on Linux and kqueue on BSD and macOS
It provides a command line interface (CLI) familiar to the discontinued mdns-repeater.
docker pull yuxzhu/mdns-reflector:latest
podman pull yuxzhu/mdns-reflector:latest
dnf copr enable -y yux/networking
dnf install -y mdns-reflector
curl -fLo /etc/yum.repos.d/yux-networking-epel-7.repo https://copr.fedorainfracloud.org/coprs/yux/networking/repo/epel-7/yux-networking-epel-7.repo
yum install -y mdns-reflector
Available in Debian 'experimental' branch:
It can happen that the version in experimental is outdated. In that case experienced users can either build the .deb package themselves
- by using this the Debian Salsa repo: https://salsa.debian.org/debian-edu-pkg-team/mdns-reflector
- by using the included debian/ folder.
Coming soon.
git clone https://github.com/vfreex/mdns-reflector
cd mdns-reflector && mkdir build && cd build
cmake -DCMAKE_BUILD_TYPE=release ..
make install
mdns-reflector
is easy to use. Just run the following command on a multi-homed host:
mdns-reflector -fn eth0 eth1
where eth0
and eth1
are the interfaces that you want to reflect mDNS for.
Run mdns-reflector -h
for help.
Similarly, run with Docker in the foreground:
docker run --net=host yuxzhu/mdns-reflector:latest mdns-reflector -fn eth0 eth1
Or run with Docker as a daemon:
docker run -d --restart=always --net=host yuxzhu/mdns-reflector:latest mdns-reflector -fn eth0 eth1
You can enable the systemd service with:
systemctl enable --now mdns-reflector
The main configuration file for the service daemon is located at:
/etc/mdns-reflector/mdns-reflector.conf
Although you can add files to /etc/mdns-reflector/conf.d/
to overwrite the
main configuration file.
Quick Tip: Adding a number and an underscore like 10_
as a prefix to your
filename is good practice and ensures a predictable priority of the config
files. 99_*
files have a higher priority than 00_*
files which means that
the settings in file 20_example.conf
would overwrite settings from 10_example.conf
.
mDNS Reflector supports multiple services running in parallel.
You can achieve this by creating files like /etc/mdns-reflector/%i.conf
.
Now enable the systemd service with this specific config file:
systemctl enable --now mdns-reflector@$(systemd-escape "%i")
NOTE: Replace %i
with your config filename without the .conf
at the end.
The .conf
filename suffix is still necessary though.
Let us define a few networks to make an example frame <iface_name>: <network_name>
:
- eth_home:
Homenetwork
- eth_smart:
Smarthome-Devices
- eth_print:
Printers
We want the devices in Printers
to announce their services into the
Homenetwork
. Likewise the devices in Smarthome-Devices
should also announce
their services into the Homenetwork
.
mDNS Reflector does not support an interface occuring in more than one reflection planes. For example:
mdns-reflector eth_home eth_smart -- eth_home eth_print # Wrong!
At the moment this is only possible if multiple mDNS Reflector services are running in parallel.
Uni-directional service announcement is not supported at the moment but is planned.
So, for this example you'll need two config files.
/etc/mdns-reflector/smarthomestuff.conf
:
INTERFACES="eth_home eth_smart"
More stuff...
/etc/mdns-reflector/printerstuff.conf
:
INTERFACES="eth_home eth_print"
More stuff...
Enabling the service of course:
systemctl enable --now mdns-reflector@$(systemd-escape "smarthomestuff")
systemctl enable --now mdns-reflector@$(systemd-escape "printerstuff")
This would make all mDNS services visible in Homenetwork
. But beware this also
makes all services from devices within the Homenetwork
visible to the
Smarthome-Devices
and Printers
networks.
Services within the Smarthome-Devices
network won't be announced to the
Printers
network and vice-versa.
Copyright (C) 2021-2023 Yuxiang Zhu me@yux.im
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.