On the router my isp provided you can set what packets go where. Which i found usefull for hosting ect to stop any lag issues.
Am i seriously dull or has that post got hardly any relevance lol?
Anyways, i myself don't think Linksys have any such feature now that i think of it, however if you use a third party software, your guaranteed to have something you can block someone with. Tell us the model of your router, and be sure to include the version.
For example, i use a WRT54G v5 which supports third party software named DD-WRT Mini ONLY due to the hardware (the RAM to be exact) not being capable of running the normal DD-WRT version.
Carefull with flashing your router (installing the new OS), there always is a slight chance you could brick your router to a state where only a JTAG? cable would be the only way to restore it. If you need any assistance, PM me.