Trust in Allah, but tie your camel. - Arab proverbIn this chapter, we shall present common problems that might be solved using a firewall implementation. In the packet filter section, we shall have a look at the ipfwadm firewalling implementation. In the application proxies section, we shall have a look at the TIS FWTK as a solution to our security problems. We shall close the chapter off by presenting a ``combined firewall solution''. This solution combines both types of firewalling and promises to produce a result greater than the sum of its parts.