IPFW firewall rule in mpd pppoe server to single pc behind router

[Ian Smith]

On Thu, 18 Dec 2008, Gloomy Group wrote:
 >  I have freebsd mpd pppoe server. Users connect to internet by giving 
 > username and password. My problem is some users put router and share 
 > internet connection with other pc. Is it possbile to disable internet 
 > sharing in server by rate limiting with ipfw firewall scripts. So 
 > that if users keep router or does nat in their pc to share internet 
 > then only single pc can access to internet. Is is possible?

Detecting that a connection is shared using NAT?  Not that I know of.

Rate limiting per connection with dummynet pipes, easy enough.  If you 
limit the bandwidth, why would you need to care how many pcs share it?

cheers, Ian