Some Well Known Ports
|135||DCOM (but not only)|
|1433||MS SQL Server|
Open Port Check Tool:
A port is the way that one can communicate with another, there are 65535 ports available to use, there are some ports that had been assigned to special, let call it, service.
In networks an open port is a port that currently use by a service and due to that it is open. An open port can be use to send or/and receive data.
An example can be your web browser and a web server, the web server use the default port 80 to listen and wait for connections. your browser establish a connection to that port, using a local port and once connected they send and receive data between them.
An open port check tool can be use to check if a port is currently open on a target machine, it can detect port forwarding status and if your server is being blocked by a firewall.
A port scanner or port checker is a tool that can be used to scan an address or even a network in search for port that are open, in computer security or hacking it is widely use to search for problematic ports that need to be close or monitor.
An open port is like an open door and with the right knowledge it is possible to use this port to enter into the remote computer.
There are some very useful tools that can be used to scan address for open ports, and even more, one example is Nmap, using it, it is possible to detect what is the operation system that behind this port including the service (process) that open the port.
Online port scanner:
The old art of port scanning is still working, even thou that today there are a lot more security method to close all the unnecessary port in the working environment, in the advanced of the web and it easy to use there are tools that can do this scanning online, the online port scanner
An online port scanner, is a port scanner like any other port scanner, the only thing in deferent is that it works from outside your network, re: a web site, it is a great tool that can be used to check if you have some unnecessary open ports on your computer/device that should be closed.
Port forwarding, also known as Port mapping, allows remote devices, like remote computers, on the web to connect to a specific port on a computer (service) in a private network. This can accomplish by enabling port forwarding on you router and forward a connection on a special port that try to connect your router.
In a basic LAN (local area network) configuration the inner devices have an IP address that is only available in the LAN, most of the time it start by 10.X or 192.X, the modem/router also have an external IP address that can get out to the internet, this mean that every device that use the inter net actually use the external IP address to surf the web, the router/DSL modem know who request the external connection (the inner device IP ) and forward the requested data to that device, this is accomplish automatic by the device.
Once you or the system administrator enables port forwarding, a device that is outside the LAN will be able to connect into one of the inner LAN connection, by assign a port in the router/modem to forward the incoming data to the relevant inner device on the desire port.