network-watcher's Introduction

Network Watcher

This is an application that acts as both client and server to monitor network connections.

It's designed to respond to other instances of itself, so you would run this in multiple machines and watch the traffic between them.

I originally created to watch the effect of Kubernetes network policies as I modified them.

Installation

To install, just run go get github.com/jmhobbs/network-watcher

Alternatively, I have a Docker image you can use at https://hub.docker.com/r/jmhobbs/network-watcher/

Usage

usage: ./network-watcher [options] hostname:port ...
  -interval duration
      time between polling targets (default 5s)
  -port int
      port to listen on (default 4444)
  -verbose
      extra output

Example

In this example run, three instances exist: isolated, unisolated and unisolated-too. The connection between isolated and unisolated-too is blocked, everything else is permitted.

$ kubectl logs unisolated-66cf5b9fc8-hn7t7
2018/02/10 17:05:41 isolated:4444 UP
2018/02/10 17:05:41 unisolated-too:4444 UP
2018/02/10 17:05:46 isolated:4444 UP
2018/02/10 17:05:46 unisolated-too:4444 UP
2018/02/10 17:05:51 isolated:4444 UP
2018/02/10 17:05:51 unisolated-too:4444 UP
$ kubectl logs unisolated-too-5468649df4-zl6vp
2018/02/10 17:05:42 isolated:4444 DOWN dial tcp 10.63.42.6:4444: i/o timeout
2018/02/10 17:05:42 unisolated:4444 UP
2018/02/10 17:05:48 isolated:4444 DOWN dial tcp 10.63.42.6:4444: i/o timeout
2018/02/10 17:05:48 unisolated:4444 UP
2018/02/10 17:05:54 isolated:4444 DOWN dial tcp 10.63.42.6:4444: i/o timeout
2018/02/10 17:05:54 unisolated:4444 UP
2018/02/10 17:06:00 isolated:4444 DOWN dial tcp 10.63.42.6:4444: i/o timeout
2018/02/10 17:06:00 unisolated:4444 UP

That's all there is to it.

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