Installation guide

STEP 11: How to audit your firewall – step by step

Prepare your test scenario

You need two computers plus your pre-configured firewall. We will call the attacking computer (from the

simulated Internet) Nessus, and the victim (our private network) Honeypot.

Figure 5: testbed for firewall auditing

Both Nessus and Honeypot will be exposed to the Internet without firewall protection (we have to assume

the worst); hence you must not use any computer for this purpose that contains any confidential data.

1 Nessus needs to be connected to the Internet:

• You can use the same broadband connection as the one your router is connected to, if

you plug Nessus into a hub between your ADSL modem (or whatever Internet

connection you have) and your firewall.

• If you have more advanced IT skills, you can simulate the Internet for testing purposes.

2 Recommended configuration for Honeypot:

• Operating system – whatever you typically use in your practice.

• Software – install all software you are using in your practice on any computer

connected directly or indirectly to the Internet (e.g. MDW, Pracsoft, all pathology

download applications, email client). Of course, you will not install any live patient data

– most software comes with demo data sets, so use these. Reminder: no software

should be installed on any of your private network computers prior to testing on

Honeypot.

• Test configuration – make sure you can browse the web and send and receive emails

from Honeypot if this is what you usually would allow in your normal practice setting.

3 Do not install any software on the Nessus attacking computer. Boot the computer from CD

without touching the hard disk of Nessus at all – in fact, it will work just as well if there is not

even a hard disk attached to Nessus.

4 Recommended configuration for Nessus:

• Any computer that will boot from CD will do.

• Configure the computer BIOS to boot from CD, usually by pressing the F2 or Del key

while booting, and then entering a BIOS configuration menu (if you don't know how to

do this, you will need professional help to do a firewall audit).