Port scans offer a simple and effective way to protect your business’s network from unauthorized access. A port, of course, is a communication endpoint. Data will travel into and out of your business’s networks through ports. Because they are communication endpoints, though, ports can provide a doorway for hackers. You can identify open ports, however, by performing a port scan.

As the name suggests, a port scan is a process that scans your business’s network for open ports. When you perform a port scan, you’ll see which ports are open on your business’s network. You can then close them so that hackers can’t use them. While they are all designed to identify open scans, there are several types of port scans.


The most common type of port scan is Transmission Communication Protocol (TCP). Most operating systems offer TCP port scans as a built-in feature. A TCP port scan will attempt to connect to the open ports on your business’s network while simultaneously recording the responses. It will send a data packet to each open port, and it will record the response given by the respective ports.


In addition to TCP, there are Synchronize (SYN) port scans. SYN port scans are more effective than their TCP counterparts. With a SYN port scan, a raw Internet Protocol (IP) packet will be generate automatically. In comparison, TCP port scans typically use the operating system’s settings. SYN port scans are often referred to as half-open scans because they don’t use a complete TCP connection.


A third type of port scan is User Datagram Protocol (UDP). With a UDP scan, each port on your business’s network will be sent a UDP packet. If a particular port isn’t open, it will respond with a message indicating that it’s not available. As a result, a UDP scan can reveal which ports are open and closed on your business’s network. UDP port scans aren’t as common as TCP and SYN. Nonetheless, some business owners and network administrators use them to defend against cyber attacks.


Finally, an Acknowledgement (ACK) port scan is one of the most unique types. Unlike all other port scans previously mentioned, it doesn’t actually reveal which ports are open and which ports are closed. An ACK port scan will only reveal which ports are filtered and which ports are unfiltered. Firewalls, for instance, are often used to filter traffic. A firewall, however, may not protect all ports from malicious traffic. If a particular port isn’t being filtered by a firewall, an ACK port scan will reveal it.

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