I had to wipe my existing OS and had to reinstall Nessus on the new BT5R3 image. However, I still wanted all my previous scan data and users to be unaffected in the new OS. So how did I do that? Here’s how:

Take a backup and restore the following folders on the new install:

1. Users Folder (/opt/nessus/var/nessus/users)
2. Master.key (/opt/nessus/var/nessus/master.key)
3. Policies.db (/opt/nessus/var/nessus/policies.db)

If you do get an error after this follow these steps to get rid of errors and just reactivate the nessus feed as follows:

1. service nessusd stop
2. /opt/nessus/sbin/nessus-fix –reset
3. /opt/nessus/bin/nessus-fetch –register [activation code]
4. /opt/nessus/sbin/nessusd -R
5. service nessusd start

Interestingly enough, I found last week that the new Nessus 4.2.0 works by default as a web interface. Gone are the days of using the NessusClient and connecting to TCP port 1241 and using it to connect to the nessusd. Connecting to local TCP port 8834 (https://localhost:8834) brings you to a web interface that you can use to connect to the new Nessus daemon. The nesssusd listener does not even listen on port 1241 by default.
I’ll shortly get used to it but I know the transition would be slow for me …. after it takes getting used to when you completely change the architecture after maintaining it for at least a good 7 years or so!