You can use apt-cache to search for package names. For example
apt-cache search smart
will deliver all packages that are related to smart. The output on my Debian machine is
smart-notifier - graphical hard disk health status notifier
smartmontools - control and monitor storage systems using S.M.A.R.T.
So you can see that the appropriate package-name is smartmontools.
Sometimes this doesn't help, in that case the apt-file tool may help. This tool is not installed by default, so you have to install and initialize it first:
apt-get install apt-file
If I now use the apt-file utility to search for restorecond I get this output:
tobi@server:~$ apt-file search restorecond
So I can see that the package policycoreutils contains the file restorecond.