The TCP wrappers provides a classical Unix mechanism which has been
designed to check if the remote client is able to connect from the given IP
address.
If » PEAR is available on your *nix-like
system you can use the pear installer to install the tcpwrap extension, by the
following command: pear -v install tcpwrap.
You can always download the tar.gz package and install tcpwrap by hand: