We use two systems. The first system acts as a Portsentry server while the other as a client. On the first system, we install the Portsentry package and on the second system we install nmap, which will be used to demonstrate the workings of Portsentry. Now we perform an Nmap scan from the client machine on the server. We can see that it works fine. After this, we configure Portsentry as per our requirements by editing various files. Once editing is complete, restart the portsentry service and then again try to perform an Nmap scan from the client on the server. We see that now the scan does not work properly.