I have been trying to learn more about packet sniffing. I realize that I can not sniff packets sent from one computer to another but from what I have read I believe that I can sniff all the packets on my network if my NIC is set to promiscuous mode. I have looked for information telling me how to do that but all I could find was a page that said I would have to write or download promiscous drivers for my particular NIC. Is that true?

Also it seems to me that Sniffing can not be done from a dial up, is that the case? If so, is it possible with DSL or cable? Last of all is it illegal to sniff a network out side your own. For instance a cable or DSL network?