i am trying code given in Unix Network Programming by Richard Stevens. but i am not able to get the code to compile.
here is the source code. http://www.cs.cmu.edu/a
I'm not on a machine where I can do this right now, but perhaps I can still help. If your distribution uses yum (e.g. RHEL):
yum provides if_dl.h
Or if you use apt (e.g. Ubuntu/Debian):
sudo apt-get install apt-file
sudo apt-file update
apt-file search if_dl.h
If apt-file is already installed, the first step won't be necessary, and I can't remember for sure if the second is. Also, I believe both package managers work both with filename and with full path.
Hopefully this will work for you or someone else reading this, and you'll get your answer!