routemonitor

Minimalist route monitoring

Reasoning

Why does this project exist?

• If you've got lots of VPNs on your computer for different servers, and you turn them on and off a bunch, it's important to make sure the routes are set up right.

• Checking the routing table doesn't work well because you're always changing connections. It just creates too much unnecessary info.

• You don't want to install anything big, e.g. Prometheus which does a lot, but you just want simple alerts for your routes without any extra weight.

• Because it's fun!

Usage

Save a config in e.g. ~/.config/routemonitor/config.yml.

fail_fast: true
route:
  - name: Single address
    ip: 10.10.10.24
    expect:
      - when:
          device: eth0
          source: 172.17.0.2

  - name: Block addresses
    ip: 10.10.10.0/30
    expect:
      - when:
          device: xeth1
          source: 10.10.10.25
      - when:
          device: eth0 # fallback if first device doesn't exist

Then run routemonitor:

routemonitor -config=~/.config/routemonitor/config.yml -verbose -json
# {"time":"...","msg":"checking route","name":"Single address","ip":"10.10.10.24/32","num IPs":1,"expects":[{"When":{"Device":"eth0","Gateway":"","Source":"172.17.0.2"}}]}
# {"time":"...","msg":"checking route","name":"Block addresses","ip":"10.10.10.0/30","num IPs":4,"expects":[{"When":{"Device":"xeth1","Gateway":"","Source":"10.10.10.25"}},{"When":{"Device":"eth0","Gateway":"","Source":""}}]}
# All routes are as expected.

In case there's a mismatch:

# ... ERROR name="Block addresses" ip="10.10.10.0/30" interface not exist expect="xeth1"
# exit status 1

Periodically run

Create a service job on a repeating schedule e.g. every 5 minutes runs with systemd.timer in Linux:

#!/bin/bash
set -o pipefail
routemonitor -config=~/.config/routemonitor/config.yml 2>&1 | tee /tmp/routemonitor.log  || \
  (notify-send 'routemonitor failed' \"$(cat /tmp/routemonitor.log)\" && exit 1)"

Installation

go install github.com/strboul/routemonitor@latest

Roadmap

• Support IPv6

• Add DNS resolver check

• Test/support other systems e.g. *BSD, Darwin, Windows (go tool dist list)