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January 24, 2009

Nessus on N810, part 2

I decided to test if Nessus really doesn't work with all the plugins.

This time I just let the device take its time and seems that it actually was able to load everything. For the first time it took almost 50 minutes for nessusd to load the plugins, but next time it takes 5 minutes. For the GUI it is a whopping 20-25 minutes every time.

Everything seemed to be OK except for the portscanning part I mentioned also in my earlier post. It didn't work even if I installed nmap and the nmap.nasl plugin on the system. After looking at nessusd.messages file, it seems that some plugins have not been installed to the plugins directory at all during the nessus-plugins compilation and install. I had to manually copy them over from the scratchbox environment.

After copying the required .nes files over to N810, I got the portscanning feature of Nessus to work. I'm however a little worried that if the scan is too agressive, this device is too slow for that and will drop packets. There is values that can be tuned for nmap, but the scan used Nessus TCP scanner. I validated the open ports as I have nmap results from an earlier run and the results matched.

As mentioned somewhere on the Nessus website, using nmap will eat a lot more memory than utilizing Nessus own portscanning, so either run the nmap scan before hand with -oG to have the open ports in a greppable form, and tell nessus to use this file for open ports, or use directly Nessus own portscanning plugin. By default it seems to use the Nessus TCP scanner.

With all the plugins the device eats up a lot of system memory so having lots of hosts to test can cause memory to run out. With my testing it was able to test 3 different hosts during the same scan, but one host and one check at a time. Because of the memory it might be justified to finetune what plugins to include in the system, and it makes things a little bit faster.

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Marko Ruotsalainen
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