You’ll agree that having connection difficulties while using the internet is annoying right? Well, one of the ways to diagnose the cause(s) is to use a port forwarding test tool.
It is a free online tool used for detecting the availability of a port. In other words, it is used to check if a port or ports are open or closed.
What are Port Forwarding test Tools?
Port forwarding test tools are free online tools used for detecting the status of a port. They can be used to determine whether ports are closed or open.
They check the external IP address and verify what ports are open on the connection. They come in handy when checking if the port forwarding is adequately set up or if the existing firewall is blocking server applications.
These tools also double as a port scanners. They can be used to scan specified networks for frequently forwarded ports.
It should be noted that certain ports like port 25 are usually blocked at an ISP level in a bid to prevent malicious activities.
There are different types of port scanning namely:
- FIN scanning
- TCP scanning
- Window scanning
- UDP scanning
- ACK scanning
- SYN scanning
- Others
For a complete understanding of the activities of an open port check tool, port forwarding tests and port blocking will be explained below.
Port Forwarding Tests
Port forwarding also known as port mapping allows a remote connection of computers to a specific service or computer on a private network.
This gives allowance for a user to run either a game server, a web server, or a service of choice from behind a router.
It also involves the translating of addresses (or port number to a new destination) and the acceptance and forwarding of packets (using routing table).
Normally, a typical router network has an IP address that is public, and the computers or servers receive an IP address that is private from the router.
This IP address is addressable only from within the network. Whenever a specific port is forwarded on a router, it implies that the router is receiving a command regarding where to direct the traffic concerning that particular port.
Port forwarding test tools are very reliable tools for verifying the success of such operations.
Blocked Ports
Port numbers range from 1 to 65535. In this range, certain ports are predefined by convention by IANA.
There are well-known ports (HTTP, SMTP, DHCP, and FTP, etc.), reserved ports and Dynamic/Private Ports. Residential internet service providers normally block ports in a bid to combat spam and virus.
Most times, port 80 and 25 are the blocked ports. Port 80 is the default port for HTTP traffic. Blocking it means the web server will be run on a port best described as non-standard.
On the other hand, for the receiving and the sending of emails, the default port is port 25.
Internet service providers usually have this port blocked with the aim of minimizing worm generated spam from infected systems within their network.