Infrastructure security check

We want to perform a security check of our Web servers architecture from the outside (Internet external access).

I'm looking for either

• a company providing such a service, please provide recommendations
• a tool that could perform exhaustive checks, without affecting the well-running of the platform

This is something we want to do on a regular basis (every 6 months).
That service or tool should be able to perform hacker-like attacks (but no DOS) in order to ensure we are not vulnerable to known hacking methods (or system not patched etc...).

From serverfault ring0

• Nessus or netsparker come to mind if you want to run them yourself. Nessus is the one that most of the Visa CISP compliance companies run.

  ring0 : Thanks. Had a look at Nessus home page. It requires a 1,200$ yearly subscription. If anyone has a preference please post it.

  halp : OpenVAS is a free alternative to Nessus.

  ring0 : Thanks for the tip.
  From karmawhore