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May 29 2008   1:44PM GMT

Firewalls Part IV – Quis custodiet ipsos custodes?

Arian Eigen Heald Arian Eigen Heald Profile: Arian Eigen Heald

Who guards the guardians? Good IT governance mandates oversight of all IT functions. The firewall tends to be neglected, because it appears to be such a back-office function that only engineers or admins actually see and work on.

However, it is one of the most critical pieces of the IT infrastructure. As a result, the following steps ought to be put in place:

1.) Administrative access – Too many shops use one ID (“admin”) and password. Each person who accesses the firewall should have a unique ID and very strong password that should be changed more frequently than the standard policy. All administrative access to the firewall should be logged, and the logs stored separately for review.

Access should be reviewed at least annually to confirm no inappropriate users have been allowed access and signed off as reviewed by management.

2.) Changes - Too often firewall rules get changed “on the fly” or as the result of a phone call from a panicked person in the board room who can’t get to his demo site or custom application. Tough nookies. All changes to the firewall rulebase should go through change controls. Emergency change controls should go further up the management tree for approval, not just the network manager. This way it’s documented as to who asked for what, who did it, and who approved. It will make people think ahead and think twice before saying, “just open it up.”

Many firewalls can be enabled to send an email every time a rule is changed, added or deleted. This should be enabled immediately so that a management person (ideally, the ISO) is notified. This will also help eliminate admins giving themselves a convenient back door into the network.

A rulebase review should be conducted quarterly with management sign-off. It helps them be aware and start to understand what a firewall is really doing for the business.

3.) Monitoring the Logs – Firewall logs are a goldmine of information. Ideally you have a system for collecting the logs for analysis and storage with a third-party application. Someone should be looking at them every day. If the organization is smart, they have a product that can store, analyze and correlate logs from servers, routers, IDSes and firewalls. One stop shopping that everyone can review – including management. (Well, you can offer!) Make sure the designated person is logged or signs off on such reviews – then your audit will be a snap.

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