Open Source Nessus Alternatives
The best open source alternative to Nessus is Metasploit. It's not free, so if you're looking for a free alternative, you could try OpenVAS or Armitage. If that doesn't suit you, our users have ranked more than 25 alternatives to Nessus and nine of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Nessus are skipfish (Free, Open Source), OpenSCAP (Free, Open Source), Tsunami (Free, Open Source) and purplepee.co (Free, Open Source).