UDP Replicator

A tiny UDP proxy that can replicate traffic to one or more endpoints.

Why?

We needed a way to take a single netflow stream and send it to multiple endpoints. As this is a generic UDP replicator, it can be used for any traffic such as netflow, syslog etc.

You could use iptables, like Zapier, but we wanted something we could easily deploy into our kubernetes cluster. There are also a number of existing UDP proxies, but non of the popular ones support replication. There are also a small number of replicators, but these all seem to be mostly unmaintained/untested toy projects with little documentation.

Usage

Direct

./replicator --listen-port=9500 --forward=192.0.2.1 --forward=198.51.100.5:9100
time="2019-09-23T14:29:50+01:00" level=info msg="Server started" ip=0.0.0.0 port=9500
time="2019-09-23T14:29:50+01:00" level=info msg="Forwarding target configured" addr="192.0.2.1:9500" num=1 total=2
time="2019-09-23T14:29:50+01:00" level=info msg="Forwarding target configured" addr="198.51.100.5:9100" num=2 total=2

The above command will:

Start a UDP server listening on 0.0.0.0 (the default) port 9500
Add a forward target of 192.0.2.1:9500 (uses listen-port for destination port as not specified in configuration)
Add another forward target of 198.51.100.5:9100

The server will start listening on 0.0.0.0:9500, any packet it receives will be replicated and sent to both 192.0.2.1:9500 and 198.51.100.5:9100

Docker

docker run -e FORWARDS=$'192.0.2.1\n198.51.100.5:9100' thomseddon/udp-replicator:1

Docker Compose

version: '3'

services:
  udp-replicator:
    run: thomseddon/udp-replicator:1
    environment:
      DEBUG: "true"
      FORWARD: "192.0.2.1\n198.51.100.5:9100"

Configuration

usage: replicator [<flags>]

Flags:
  --help                 Show context-sensitive help (also try --help-long and --help-man).
  --debug                Enable debug mode
  --listen-ip=0.0.0.0    IP to listen in
  --listen-port=9000     Port to listen on
  --body-size=4096       Size of body to read
  --forward=ip:port ...  ip:port to forward traffic to (port defaults to listen-port)

All configuration params can be passed as arguments as shown above, or as environment varaibles (as shown in usage above) - where environment variables are uppercased snake case e.g. LISTEN_IP