Open Port Check Tool - Open Port

Open Port Check Tool

Open Port Check Tool

Open Port website is a free Open Port Check Tool to check a remote TCP port state – open or close. The tool can also be use to test your router or device for port forwarding.


Domain/IP: Port:

Please provide a Hostname and a port number to check, the default that you see are your ip address and the default Http port number 80:

Check other fee tools we have:

Some Well Known Ports

Port Number Description
21 FTP
22 SSH
23 Telnet
53 DNS
110 POP3
135 DCOM (but not only)
1433 MS SQL Server
1521 Oracle Listener
25565 MySQL
For a full list of port numbers refer to Wikipedia – List of TCP and UDP port numbers

Open Port Check Tool:

A port is a number that represent an entry to a service that is open to the network.

There are 65535 ports available to use. Some of the ports had been assigned to special service by INAN (Internet assigned numbers authority).

In networks an open port is a port that currently use by a service. An open port can be use to send or/and receive data.

There are two types of ports, TCP ports and UDP ports. Open port check tool can check the state of TCP port.

This can be done by sending a packet using the Ipv4 (IP version 4) protocol.

An example can be your web browser in the client side and a web server as the remote server.

The web server use the default port 80 for HTTP or port 443 for HTTPS 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 is like a port test, using this tool can also detect the port forwarding status.

You can also use open port check tool to remotely check if your server is being blocked by a firewall.

Port Scanner:

A port scanner or port checker is a tool that can be used to scan a range of 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 or a window. With the right knowledge it is possible to use this port to enter into the remote computer.

Using and running a regular port scan is a method to find that ports in the port range and block them.

There are some very useful tools that can be used to scan the network address for open ports. Using such tool can even find address inside the organization that need to be removed.

An example to network ports scanner tool is Nmap. Using it you can scan full subnet and it support several scan methods like the TCP SYN scan and the TCP ACK scan .

Advanced usage of the tool can detect what is the service (process) that open the port and the operation system that behind this service.

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 and monitor all the ports in the working environment.

An Intrusion detection system (IDS) can be use to monitor the network.

With the advanced of new tools, like an online port scannerusing the web as the source to scan an environment..

An online port scanner is a port scanner like any other port scanner, the only deferent is that it works from outside your network. re: a web site – online.

It is a great tool that can be used to check if you have some unnecessary open ports on your computer/device that needs to be closed.

Port forwarding:

Port forwarding, also known as Port mapping, allows remote devices, like remote computers, to connect to a specific port on a computer (service) in a private network.

This accomplish by enabling port forwarding on you router and forward a connection on a special port that try to connect your router.

You also need to enable it on your windows firewall or the Unix IP table.

Firewall design for blocking inbound and outbound traffic by closing ports and monitoring the data against malicious activities.

In LAN (local area network) configuration the inner devices have an IP address that is only available inside 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 and forward the requested data to that device.

This is accomplish automatic by the routers.

Once port forwarding is enable, device that is outside the LAN will be able to connect into the inner LAN.

This is done by assign a port in the router/modem to forward state. Once done the incoming data forward to the relevant inner device on the desire port.

Did You Know:

To check for list of ports that currently open on your host and to see what are the IP addresses or the host that your computer is connected to, you can use the build in command line tool netstat it is one of the build in network tools.


Other useful tools:

Online Ping Test – Free tool to ping a website.
My IP Address – Want to see what is your internet IP address, check here.

  • Registration to the site is Free and Open

  • Recent Posts