Next-generation firewalls are all-in-one firewalls. They have all the security features, such as IPS, antivirus, anti-spam, and reputation filtering, in a single box. In this section, we will discuss a major security feature, which can prevent us from getting our shell on our target. Now, let's assume that we were able to plant our Python reverse shell successfully on our target machine. Now, in a traditional firewall, if the access control list (ACL) was allowing the traffic to the outside, then we will get our shell back successfully. But if the firewall was doing reputation filtering, then what will happen is that once the client initiates a session back to our Kali machine and reaches the firewall, the firewall will do a lookup and check on the destination IP. Then, it checks whether the destination IP belongs...