ZRE protocol implementation

Peer-to-peer local area networking with reliable group messaging and automatic peer discovery.




Clone and test:

git clone
cd zre
stack build
stack exec zre
# in another terminal or networked computer
stack exec zre
# optionally install zre binaries
stack install

Two zre peers should find each other and be able to send message between each other. Firewall needs to allow traffic on UDP port 5670 and TCP port range 41000-41100. Application picks random port from this range and advertises it to network.


Few applications are provided to get you started:

  • zre - interact and dump events
  • zrecat <group> - cat messages for group

These can be installed locally with stack install command.

Try running multiple copies of zre and zrecat on the same computer or computers on the local network:

# another terminal
zrecat test
# now in original terminal you can join testgroup with
> /join test
# or send messages to it
> /shout test msg

Send uptime periodically to uptime group:

( while true; do uptime; sleep 1; done ) | zrecat uptime

Cat file to group:

cat /etc/os-release | zrecat test

Interact manually:

# in zre shell following commands are supported:
> /join time
> /shout time test!
> /leave time
> /join uptime
> /whisper <uuid> message


Implementation of gossip protocol is included in form of key value TTL server. This allows connecting peers from different networks (or subnets) not reachable via multicast beacon. This service requires TCP port 31337 and can be started with zgossip_server binary.

Run server:


Pass gossip endpoint to apps with:

zre -g <gossip_ip>:31337


ZRE applications using runZre will automatically try to load configuration file if ZRECFG environment variable points to it. See zre.conf for configuration example:

ZRECFG=./zre.conf zrecat test

To be able to use one config for multiple apps and still be able to distinguish between them you can also set ZRENAME environment variable which overrides name from config or default config if ZRECFG is not used:

ZRENAME=zrenode1 zrecat test