An IP Port Checker is a tool that can be used to scan the open and closed ports of a given server. Such a checker also determines that type and variety of the services running on the target server.
The Port Checker is used by administrators inspecting their own networks. In doing so, the administrators strive to ascertain the security of the network and to ensure that the network is not vulnerable to attacks. On the other hand, potential attackers may also use an IP Port Checker to scan a server and identify any open ports or other vulnerabilities which can be exploited.
How does An IP Port Checker work?
The way a server responds to the data or requests sent to it reveals the ports that are open and other details about it. So an IP Port Checker, also known as a Port Scanner, will send raw data packers to the target server.
The way the server responds to these packers will help the Port Checker determine many details. These include the open and closed ports, the operating system running on the server as well as whether or not the server has enabled a firewall.
When you are using a Port Checker, you are prompted by the tool to provide basic information. This includes the IP address of the target server as well as the range of ports you want to listen to. Once you enter this information, the tool starts sending raw data packets to the IP address provided and then listens to the ports you have specified. It then tells you which ports are open and which are closed.
Types of Scans
An IP Port Checker can be used to perform a wide range of scans on the target server. Some of the most notable of these include SYN Scanning, TCP Scanning, UDP Scanning and Window Scanning. Here is a brief overview of each.
SYN Scanning: This is a rudimentary port scanning technique. In SYN Scanning, the scanner tool sends raw IP packets to the target server without actually forging a TCP connection. So this type of scanning is able to determine the open and closed ports with full control of the data packets and with minimal activity on the part of the target server.
TCP Scanning: TCP Scanning is another simple scanning technique when it comes to port scanning. Unlike SYN Scanning, TCP Scanning involves interacting with the network functions of the operating system running on the target server. In doing so, the scanning tool performs a three-way TCP handshake with the server. This type of scan is usually not as preferable as SYN Scanning, especially if the scanning tool simply wishes to listen to the ports.
UDP Scanning: Another type of scanning performed by an IP Port Checker is UDP Scanning. UDP scanning is somewhat different from TCP and SYN Scanning.
In this particular type of scanning, a UDP packet is sent to the target port. If the port is closed, it will automatically respond with a message that the port is unreachable. If the port does not respond with such a message, it is automatically assumed that the port is open.
Apart from directly interacting with the server ports, UDP scanning may also interact with the application layer by sending out application-specific UDP packets. This method is more effective at finding open ports at the application layer level.