5.3.2.5. RAYNET Private DMR

In order to learn more about how DMR works, I set about trying to implement my own server. I first looked at Brandmeister and Phoenix, could I download and run my own? No, they are closed systems.

Searching around I came across HBLink3. I found lots of references to it and even a few forks.

I quickly set up a simple bridge in a docker container, and was able to handle a conversation. I invited a few other people on play as well, and quickly discovered that all traffic was sent to all peers (Pi-stars) registered. This turns out to be by design.

5.3.2.6. HBLink DMR

5.3.2.6.1. Multiple Talkgroups

With some simple changes I’ve been able to enable multiple talkgroups using HBLink as the foundation.

5.3.2.6.2. Building and Running

I’ve built this using docker. HBLink does have a “Dockerfile” however the way it’s setup doesn’t work for me, as you have to have a separate repo to store the configurations. I’ve therefore created my own Dockerfile which builds a self contained image.

FROM debian:buster-slim

RUN apt-get update && apt-get install -y git python3-twisted python3-pip \
    python3-bitstring python3-autobahn python3-jinja2 libnet-ifconfig-wrapper-perl \
    procps wget && \
    rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

WORKDIR /opt

ADD https://ham-digital.org/status/DMRIds.dat /opt

RUN pip3 install dmr_utils3 bitstring bitarray configparser

RUN git clone https://github.com/n0mjs710/HBlink3.git
RUN git clone https://github.com/sp2ong/HBmonitor.git

ADD entrypoint.sh /entrypoint.sh
RUN chmod +x /entrypoint.sh

WORKDIR /opt/HBlink3
# copy config
COPY conf/* ./

COPY script/* ./

WORKDIR /opt/
COPY monitor-config.py HBmonitor/config.py

RUN useradd -ms /bin/bash radio && \
    chown radio:radio /entrypoint.sh && \
    chown -R radio /opt

RUN mkdir -p /var/log/hblink/
RUN chown -R radio:radio /var/log/hblink

#USER radio
EXPOSE 62030/udp 62031/udp 42001/udp 8080 9000 8090

ENTRYPOINT [ "/entrypoint.sh" ]

The same container image is then run multiple times

• HBlink
• YSF Peer
• Monitor

Depending on the entrypoint.sh script and command sent defines which function is run.

cd /opt/HBlink3
IPADDR="$(ifconfig eth0 |grep -A 1 'eth0' |tail -1 |cut -d 't' -f 2 |cut -d ' ' -f 2)"
sed -i -e "s/HOSTIP/$IPADDR/g" /opt/YSF2DMR.ini

case "$1" in
  bash)
    bash
    ;;
  hblink)
    python3 raynet.py
#    tail -F /opt/HBlink3/hblink.py
    ;;
  monitor3)
    cd /opt/hbmonitor3
    python3 monitor.py
    ;;
  monitor)
    cd /opt/HBmonitor
    python3 monitor.py
    ;;
  playback)
    python3 playback.py
    ;;
  ysf2dmr)
    wget 'https://ham-digital.org/status/DMRIds.dat' -O /opt/DMRIds.dat
    /opt/YSF2DMR /opt/YSF2DMR.ini
    ;;
  *)
    echo $"Usage: $0 {blink|monitor|monitor3|playback|ysf2dmr}"
    exit 1
esac

In the end I found the hblink code while very nice and complete would become a limiting factor in with the direction I was heading. So in decided to start from scratch. Having made that decision I was then free to pick a different language. I wanted to fast and preferable a compiled language. I came across golang from google.

5.3.2.7. Building from scratch

After further looking around I decided that I might be better off writing my own system. I had a few basic requirements

• Small
• compiled code for performance
• minimum additional packages required
• Run in docker containers
• carry multiple concurrent calls directing traffic to required hotspots only
• Authenticated hotspots only
• Only pass traffic for known DMRIDs
• Unlimited Talkgroups
• ACL (Access Control List) to manage access to Talkgroups

I chose to use “Golang”. I Read through the tutorial in the morning and started writing the server in the afternoon. In all it took 2.5 days to write the basic DMR handling service and hook it into the management portal.

5.3.2.7.1. Design

Using Ruby on Rails for the GUI was again a simple choice, it provided for a rapid development, testing and deployment.

5.3.2.7.2. Management Portal

Allowing multiple talkgroups is just the start, next is to provide a management interface for

• Registration
• Secure access
• See talkgroups
• Set and unset static Talkgroups
• Define who can access which talkgroups
• Monitor talkgroup activity

I plan to use Ruby on Rails to build this side, with either mysql or CockroachDB. Mysql is simple to run, but doesn’t scale too well. CockroachDB works well inside docker containers, and can scale very large if necessary. As this system will handle queries for every conversation start it’s important that it responds quickly.