Blocking ip range in hosts file?

Question

I know how to edit my hosts file on osx, how can I block the range 78.31.8.0/22? What do I put in the hosts file?

Answer 1

You cannot.

/etc/hosts is not for blocking – it is for translating domain names to addresses (when other methods are unavailable) – more specifically, an exact name to a single address. If a program tries to access the address directly, the system won't even touch /etc/hosts, because there will be nothing to look up.

Use a proper firewall, such as ipfw.

Answer 2

A simple way to null a range of ip is:

route add 78.31.8.0/22 lo

Use the routing table to do it :)