[bada_bing]

Originally Posted by Logician

MAC address are NOT used in the internet. They are for local networks..

Besides how can you assume that one has such an address? There are millions of internet users without an ethernet card and connected to the internet. Since ethernet card is not a requirement to connect to internet, NICs are not used in the TCP/IP communication either. The only requirement of a TCP/IP protocol is to use an IP address and this is the only information you can get from an internet user in most of the cases.

In NO cases you can get his NIC number on the internet unless he is a local user or he is using some sort of "weird" software that is intentionally posting this information. (I dont know such software either)

What are you talking about? Everyone that is connected to the internet besides dial up users need a NIC card so that their IP address can bind to it. There is no other way myfriend. For every NIC card there is a unique MAC address assigned to it unless they are doing MAC Address spoofing. Most people today are accessing the internet using a broadband connection rather it be DSL,cable modem or Wireless.
All devices are required to have there IP bound to a NIC card.

Now some of the issues are NAT if a user is behind a NAT device such as a Router/ Firewall then the typical IP Address of that user will be the external IP address if that device and not the NAT address on the other side of the router/Firewall.. Hope I didnt confuse anyone..

Now the only way I coule think of accessing the actual users IP Address and the MAC address is to use activeX controls and access there credential that way. So the hack would have to be able to activate some activex controls on the PC that is logged into your forum, so the exchange would happen durin the login process...