If you've recently installed phpNuke with Fantistico (it's at the bottom of your Control Panel – if you haven't seen it – go look), you may have noticed that the phpBB version is about 5 releases out of date.
The most recent version of phpBB is 2.0.21, but the version within the phpNuke 7.8 Release is 2.0.15. However, before you run out and download the standalone updates/patches for phpBB, please keep reading.

This is a special version of phpBB that is designed to run inside and with phpNuke, so DO NOT simply patch phpBB with the "official version" from phpbb.com. This WILL break some of the functionality of the embedded version. Your gonna have to do a little bit of work, but it'll be worth it. You will be required to download some files, unzip them, upload to your webspace, and then run 4 URLs from your browser.  Please note that this is a file-by-file update – and you cannot patch all in one fell swoop. It still will probably only take 10 minutes – and you'll have a much more secure version of phpBB.

Here are the steps:

Go to http://www.nukeresources.com/download-search-.html , enter "BBtoNuke" in the search box. (I don't think you can hotlink directly to the files, hence the required search).

Then look for the following files:

BBtoNuke 2.0.16
BBtoNuke 2.0.17
BBtoNuke 2.0.18
BBtoNuke 2.0.19
BBtoNuke 2.0.20
BBtoNuke 2.0.21

(do not get the files with the NP extension)

Save these files to your local PC. Unzip them one at a time (I'd do each one in a seperate temporary directory), fire up your FTP program and upload the files to the root directory on your AUSWEB hosting account (assuming that you have installed phpNuke to the root directory).

Make sure to keep the directory structures intact. Now, from your browser, run the various updater files. The URLs will look like this…

http://yourDOMAIN-phpnukeinstall.com/update15-16.php
http://yourDOMAIN-phpnukeinstall.com/update16-17.php
http://yourDOMAIN-phpnukeinstall.com/update17-18.php
http://yourDOMAIN-phpnukeinstall.com/update18-19.php
http://yourDOMAIN-phpnukeinstall.com/update19-20.php
http://yourDOMAIN-phpnukeinstall.com/update20-21.php

Note that you'll have to update in the order as show above and it's an incremental, file-by-file update.
So you'll be updating to verion 2.0.16, then 2.0.17, then 2.0.18, then 2.0.19, the 2.0.20 and 2.0.21 (if you choose).

Now, you have the latest version of phpBB running with your PHP-Nuke install and you haven't broken anything!

Dont forget to delete the update php files after you are finished (update16-17.php – update20-21.php)

Here's a few extra links to some phpNuke resources: