A Windows port scanner is generally the most important tool used in detecting the open ports of a Windows-based computer or laptop.
All computers connected to the Internet send and receive information through ports. There are 65535 ports available, but not all of them are open or active at the same time.
How Windows port scanner works
A port scanning tool basically works by transmitting specific requests to the target computer connected to the network with the sole purpose of determining which ports are open.
The information from the port scanner is used by network administrators for security purposes. Unfortunately, hackers can also use the information from port scanners to find vulnerabilities in computer and exploit them.
Every computer connected to a network, whether it is a local network or public network, has a specific IP address. On each IP address or computer, are services running. These services, which could be software’s or programs like servers linked to emails clients and gaming servers, use ports on the host computer to connect to the Internet.
A Port scanner, therefore, simply detects which services are active and on which specific ports.
Types of Port scanning
There are different types of Port scanning. A good port scanner must be able to do any of the following types of scanning:
SYN scan generates a number of IPs, then sends it out to the targeted network or system and waits for a response from the host computers. A targeted host with an open port would respond back with what is known as SYN-ACK signals.
While the SYN scans wait for a response from open ports, FIN scans can bypass security firewalls and prompt a response from closed ports.
ACK scans do not actually look for open or closed ports. What is does is simple but very effective. It scans for the presence of a firewall in the host system.
However, very good firewalls would not allow a security breach using this strategy.
The most basic Windows port scanner would use this method if the SYN scan is not an option. TCP scan uses the features of the operating system to find an open port.
Though most port scanners use this method, it is not the most reliable. UDP port scanners, generally speaking, report that a port is open if there is no response from the scanned port. The obvious downside is, if a good firewall is blocking the port, the scanner would send back an ‘open port’ report.
Port scanning tools
A Windows port scanner is not hard to get. As a matter of fact, there are several of these tools available online. Some of them are free while others can be gotten for a fee.
It should be noted that the free tools can be very effective in scanning ports. Professionals and hackers with malicious intent generally opt for paid tools as they are more effective and can be customized to do particular tasks.