Advice 1: How to test the port

To exchange information in a network transport Protocol TCP establishes connections between applications running on computers. In the address field of each packet data includes a numeric identifier that indicates which application will process the information. These numeric identifiers are called network ports. They are numbered in the range from 1 to 65535.
How to test the port
Instruction
1
To find out which applications and processes occupy ports on your computer, you can Windows tools. Start a command prompt from the start menu and type cmd. In the console window, type netstat –a –n –o
The command will list all active connections TCP and UPD ports and processes. In the column "Local address" is the IP address of your computer, a colon, the port number involved in the process from the PID column. "External address," reports the address of the remote host and port that listens to the relevant application.
How to test the port
2
To find out the process name by its number, the key combination of Ctrl+Alt+Delete call window "process Manager". Click on the "task Manager" and go to the tab "Processes". Each number in the PID column corresponds to the name of the process or application in the column "image Name".
If in the window "task Manager" does not list the PID in the main menu, choose the commands "View" and "Select columns". Check the box "Ref. the PID (process identifier)".
How to test the port
3
To check availability of any port, enter the cmd command prompt. In the console window, type telnet. The next line prompted to work with this team. Dial open , where domen_name – your domain name, and port_number is the port number.
If the port is closed, you will see a failure message: "failed to open connection to this node, the connection fails". If a team enters into a dialogue and generates valuable information – the port is open.
4
Ports protect the computer from unauthorized program actions-firewalls, or firewalls. It is sometimes necessary to open a port to communicate with another node. If you have enabled the built-in Windows firewall, via "control Panel" go to "Network connections". Right-click on the icon of Internet connection to display the context menu . Choose the command "Properties", go to the "Advanced" tab and click "Settings".
5
In the window "Windows Firewall", click "Add port". In the Name field, enter a description of the application, which will occupy the port in the "port Number" is an arbitrary number. If your version offers a choice of TCP and UPD, perform the procedure twice. If you add a port to work with a particular application, click the "Add a program" and specify the network path by clicking "Browse" or "Change scope".
How to test the port

Advice 2 : How to check the port is available

The solution of the problem of the availability check in port operating system Microsoft Windows 7 can be found in using the Microsoft Telnet client that enables users to establish a TCP connection to the local host via 127.0.0.1 verifiable port.
How to check the port is available
Instruction
1
The main menu of the operating system Microsoft Windows 7 by clicking "start" and change the value to telnet to the box of the search string to perform the operation of starting the client.
2
Click "Find" and open the context menu of a found item telnet.exe click the right mouse button.
3
Specify the "Run as administrator" and confirm your choice in the request window "UAC" by clicking "Yes".
4
Specify the value of the administrator password in the pop-up window prompted to confirm their authority or use an alternative method of starting the client.
How to check the port is available
5
The main menu of the operating system by pressing the "start" button, and specify a value cmd.exe in the text box of the search string.
6
Click "Find" and open the context menu of a found item, click the right mouse button.
7
Specify the "Run as administrator" and confirm your choice with the introduction of the password values in the request window system.
8
Specify a value in the text box, telnet command line and press Enter to confirm the command.
9
Enter a value of o or open 127.0.0.1 in the window command interpreter of the Microsoft Telnet client and confirm the command by pressing the function key Enter.
10
Wait for the window cleaning client (in the case of a connection) or the message on impossibility to establish the connection (if local port is unavailable subject to verification) and use the following commands to define the necessary settings:
- ?/h is for help;
- to end the active connection;
- u - to reset;
- d - to display the parameters;
- st to display the current status;
- o port_number - connects to the selected port;
- sen - to send the selected rows to the server.
- q - for the completion of the client;
- set - to determine the necessary parameters.
How to check the port is available

Advice 3 : How to check if a port is closed

Internet applications send information using special ports. The network port is allocated a system resource to running on a specific network host. If the port is closed, the program will not be able to go online, and therefore can not properly perform its functions.
How to check if a port is closed
Instruction
1
To check closed ports, you can use standard Windows tools. Go to the settings used programs, which can't successfully connect to your server, go to network settings. Remember you specified in the settings of the port.
2
Start a command prompt. To do this go to "start" - "All programs" - "Accessories" - "Command prompt". Also you can enter cmd in the search bar, application, start menu, and then select the found result.
3
Enter the command netstat. This app allows you to view the list of running gateways through which the Internet connection on your computer. Press Enter.
4
You will see a list of all active connections at the moment. The port number you can find in the first column. It is indicated after a colon, preceded by the IP address. If this list used by your application network gateway is not specified, it is closed.
5
Enter in the settings of the programs used one of the open ports listed in the list, or try to open it using the standard tools of the system. Go to menu "start" - "control Panel". In the opened window, select the search bar and enter "firewall". Among the found results, click "Windows Firewall".
6
Click the link for "more options", then click "inbound Rules" - "new rule". Follow the wizard and create a new incoming connection with a port number that uses your app.
Note
Open the gateway for an application only if the program you used, and you just know that she poses no threat to the security of the system. It malware software uses non-standard ports. When you use suspicious programs never disable the antivirus program and firewall.
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