How override a network filter with portableapps

That's not the purpose of PortableApps. It's designed to allow you to carry around your favorite applications on a usb drive, not bypass a network filter.

what your teacher meant when he pointed you to this site.
In general, when there is a website and content filter on your schools gateway to internet, then it does not matter if your browser is installed on the schools computer or on the usb stick, it will have to pass the filter and therefore it is no solution for you at all. The filter simply can not be bypassed so simply, if it could by bypassed by just installing some app on a usb stick, nobody would bother to install such filter any more.

There are some ways to bypass some filter functions. If it is for visiting some websites only, TOR-Browser might be a partial solution in some cases, this is provided by the tor.org itself, not this site directly.

http://www.torproject.org/projects/torbrowser.html.en

But **do read all the instruction and docs** there so you know what it is about really and not think this is some kind of ultimate encryption of any traffic from your PC to the outside world.

Maybe you can bypass the netfilter by using different proxy settings.
This works only in realy weak secured networks, but because some schools are low on budget, its worth a try:

Most schools install a proxy server to manage content-filtering. But some few don't spent money in real administrators who know what the're doing, and so it's possible that they didn't block internet-access without that proxy.

So you could use a firefox-portable (or any other portable browser), where no proxy server is set by default, to try connecting to the internet.

Maybe this is what your teacher wanted to tell you ...

Another possibility is that they use browser-settings or additional software to prevent you from changing the browser settings. In this case a portable browser is also your friend because you have the rights to make changes to all settings in it.
But in this cas you'll ned to know what settings you have to make to bypass the filter.
Maybe the school provides another proxy without filter for the teachers, and maybe this also needs an authentification ...
In this case, it would be best, if you talk to your teacher, again.

When i studied some years ago, my college had set a netfilter, too.
We bypassed it by renting a vServer (which url was not blocked by the college), installed a proxy on it and connected our browsers to that proxy to enter the web.
we used portable browsers which had set our own proxy as the default proxy server.
But to do this, you need someone who pays for the server and someone who knows how to deal with linux and squid. And most important, because such a proxy is accessable from the internet, you'll need to activate authentification on this server to prevent some hackers to use your proxy to redirect their dirty work through your proxy. If this would happen you coulld get into real trouble!
So dont do something like that until you realy know what you're doing!!