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  • Ports

    hello
    Would you like to tell me that what is meant by port and what are open ports and in windows 2000 server how could i check that which ports are open in my system and how could i open/block the specific port in windows 2000 server
    Thanks

  • #2
    A port is basically a doorway into your computer. When an attempt is made to connect to your computer it must occur on a port. A simple analogy would be - Your IP address is your street address, and the Port is your front door, and your side or back door each as another port. In TCP/IP and UDP networks, a port is an endpoint to a logical connection. The port number identifies what type of port it is. For example, port 80 is used for HTTP traffic.

    You can check from the command prompt for open in-use ports using NETSTAT.

    NETSTAT -a will show all ports which have an application listening on that port.

    To block/close a port you can use a TCP filter in the NIC properties. The problem with this is that you can only select what you want to allow. It will block everything else, so if you wish to allow port 80 you can add that to the list. Port 81 however will be blocked.

    If you want more control over what ports are open/closed you should use firewall software. Zone Alarm Basic Edition is free, check it out.

    http://www.zonelabs.com
    Andrew

    ** Remember to give credit where credit is due and leave reputation points sigpic where appropriate **

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    • #3
      hello
      thanx for your reply yes i have succesfully run the netstat -a command on my system and in the result it gives me different field such
      as proto,local address etc..
      For example some rows in it looks like this
      Proto localaddress foreign address state
      TCP mbbs:netbios-ssn scl-proxy:0 listening
      TCP mbbs:1058 scl-proxy:3788 established
      UDP mbbs:microsoft-ds *.*

      mbbs is the name of my computer.

      my questions
      1- what is meant by listening and established.
      2- what is meant by microsoft-ds and *.*
      3- what is meant by foreign address
      4- how could i block the application listening on local address mbbs:1058 and how i check that it has been blocked.
      5- how could i change the port number for example how could i change theh local address 1058 to another.

      Thanx


      Comment


      • #4
        Originally posted by shahryar ahmed
        ...
        For example some rows in it looks like this
        Proto localaddress foreign address state
        TCP mbbs:netbios-ssn scl-proxy:0 listening
        TCP mbbs:1058 scl-proxy:3788 established
        UDP mbbs:microsoft-ds *.*

        mbbs is the name of my computer.

        my questions
        1- what is meant by listening and established.
        2- what is meant by microsoft-ds and *.*
        3- what is meant by foreign address
        4- how could i block the application listening on local address mbbs:1058 and how i check that it has been blocked.
        5- how could i change the port number for example how could i change theh local address 1058 to another.
        1. Listening means that a program is awaiting a connection on that port, established means another computer is actively connected. That doesn't mean however that it is currently transmitting data (it could be), but it could be that it is keeping the connection alive.

        2. Netstat is funny because it lists the name of the service as the port for the typical application. microsoft-ds is actually operating on TCP port 445.
        To get a list of the port and program that is using it use this application - Active Ports. *.* means the foreign address is a broadcast address, this is the nature of UDP.

        3. Foreign address is the address that is connected to the local port. It can be a local address if it is listening.

        4. You can close the application so that it is no longer utilizing that port, or use firewall software to reject the applications request to access the port.

        5. If you want to change what port a program uses you'll need to alter the application settings. If its hardcoded it may not be possible.
        Andrew

        ** Remember to give credit where credit is due and leave reputation points sigpic where appropriate **

        Comment

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