Millipede 0.3

Millipede is a high-performance NTRIP caster written in C for the CentipedeRTK project, a network of RTK bases based in France (see https://centipede.fr).

Millipede uses libevent2 for minimal memory footprint.

It can easily handle tens of thousands of NTRIP sessions on a minimal server.

Currently runs on FreeBSD.

Features:

• "Virtual" base algorithm which picks the nearest base from the source table
• High performance
• Low memory footprint
• Supports IPv6 and IPv4
• NTRIP proxy to fetch from an external caster
• On-demand stream subscription

The current version requires:

• libcyaml
• libevent2
• json-c

Dependencies

FreeBSD: sudo pkg install libevent libcyaml json-c

Building

cd caster; make

Installation (FreeBSD)

As root:

1. Create a caster user: pw useradd -n caster -d /nonexistent -s /bin/nologin
2. cd caster; make install
3. Create configuration files in (default) /usr/local/etc/millipede/, samples in sample-config/.
   • caster.yaml main configuration file
   • sourcetable.dat our local sourcetable
   • source.auth authentication of sources from our sourcetable
   • host.auth authentication as a client to other hosts
4. mkdir /var/log/millipede && chown caster /var/log/millipede
5. install -m 0755 sample-config/caster.sh /usr/local/etc/rc.d/caster
6. sysrc caster_enable=YES

Running

service caster start, or start the /usr/local/sbin/caster binary.

Documentation

There are 3 main functions the caster can fulfill simultaneously, configured from caster.yaml.

Regular NTRIP caster

Configure sourcetable.dat for the local sources, source.auth for their authentication, and the listen section for the IP addresses to listen on.

NTRIP proxy

Configure the proxy section with a reference caster.

The local caster will fetch the sourcetable from the reference caster at table_refresh_delay (in seconds) intervals, and announce it merged with its own sourcetable.

Sources will be fetched and served to clients on-demand from the reference caster.

"V" base

Should be declared in the local sourcetable (see default config) with its "virtual" field (12th field) set to "1".

When a NTRIP client connects to this base and announces its location through $G*GGA NMEA lines, the caster will serve it the nearest base from its general sourcetable (local + proxy), switching over time when the client moves.