|First, secure your Buffalo router so nobody else can make changes to it. Use a complex password known only to you on the administrative interface and disable wireless access to the admin interface. If you do, and you're the only person who can access the admin interface, the only other change anybody else could make would be to reset it to factory defaults.|
To answer your question, it's not really possible with low-end SOHO level equipment. Especially if you don't secure access to the administrative interface.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.