GeezerVison

In computer networking, a mangled or invalid packet is a packet—especially IP packet—that either lacks order or self-coherence, or contains code aimed to confuse or disrupt computers, firewalls, routers, or any service present on the network.

Their usage is associated with a type of network attack called a denial-of-service (DoS) attack. They aim to destabilize the network and sometimes to reveal its available services—when network operators must restart the disabled ones.^[1] Mangled packets can be generated by dedicated software such as nmap.

As of 2008, most invalid packets are easily filtered by modern stateful firewalls.