How to get ifup/ifdown source code

[Patrick Dahiroc]

i'm curious to know how ifup/ifdown does it's magic.  how do
i get the source code for these using apt-get

-- 
"As a general rule, if you have trouble 
 with the binary system, then probably it 
 is because you do not really understand 
 the decimal system ..."
                R.W. Hamming