These are much more interesting to execute in contrast to passive attacks. DoS (denial of service) attacks, for example, occur when you flood a network with packets. The server is focused completely on processing incoming packets to the point it can no longer handle legitimate traffic. The server is flooded and eventually freezes. MITM attacks are typically carried out to capture data packets intended for other computers. This is executed by first employing a DoS attack and then spoofing the intended recipient’s IP address. The server sees the MITM as the friendly computer and relays traffic intended for the friendly to the MITM. It looks like this:
Regular transmission: Some Corp (192.168.2.3) <==data==> Friendly (192.168.2.10)
MITM Transmission: Some Corp (10.10.2.3) <== intercepted data==> MITM (Real IP (192.168.2.5 w/ spoofed IP 192.168.2.10)
Of course this type of network security attack is extensive, but the actual method is outside the scope of this topic. The complexity of this attack depends on who the intended victim is.
Hopefully, this has enlightened the curious and uninformed. Furthermore, depending on the context in which certain methods are employed, simple reconnaissance can easily turn into an active network security attack. They can go from being legal to very illegal so use caution. If you are interested in studying network security and network security attacks do it in a controlled environment. Be safe and happy computing!