turn off those ppp0-n

[Nx]

first i wanna 10Q 4 helping me with connecting my ADSL 2 the net now, i after i turn it off(the progs:pppd,pptp) i cant get it back on and i get in the ifconfig -a ppp0,ppp1 and so on they wont come off with the ifconfig pppn down what's the problem?     PS how do i secure my box better?