If you run an open server that allows anyone to register and join the server you may be faced with those that wish to spam your client base with URL's advertising products or other sights. URL filtering is a system that allows you to specifically deny hosts based on masks and wildcards.
ADD - Adds a URL.
ALL - Filteres all messages.
CHANNEL - Filters only channel messages.
DEL - Deletes a URL.
LIST - Lists all filtered URLs.
NONE - Turns of filtering.
NOTICE - Sends a notice for each URL filtered.
STATS - Statistics on the number URLs that have been hit.
/as help security urlfilt <topic>