What's Port 445 in W2K/XP/2003

I have a small setup of Windows 2003 server in my office. Our network consists of Windows 2000 and Windows XP client computers. I have usually the habit of checking network statistics on each computer that I go before I start my work. All the time I have noticed port 445 occurred in the statistics and I do not understand what function it does. Can anyone tell what is port 445 used for on W2k/XP/2003 computers and can I stop it?

I am not sure about what port 445 does because I can't find it on my Windows XP computer. However, if you want then you can definitely close it. The below is the way to close it in Windows XP. For others you have to manipulate it.

Start - Run - type "regedit" and press Enter. Navigate to HKLM\System\CurrentControlSet\Services\NetBT\Parameters. Look for "TransportBindName" registry entry and right-click on it and select "Modify". Under "Value data:", delete its content and leave it blank. This will close the port. Save it by clicking on "OK" button. Exit the registry and reboot your computer.

No don't close port 445. It is important and is used by system processes that provide widely-used types of network services. Port 445 is a service message block used for file sharing on Windows XP, 2000, 2003, ME, and other SAMBA-related connections. It is used by various operating systems to give security options at high levels. The port 445 scans the system typically for shared files that outside users try to harvest into the computer's system.

Is it currently opened or closed? If it is closed or taking too long to get open then you have to manually open it. In Windows 2000/XP/2003, Microsoft added the possibility to run SMB (Server Message Block) protocol directly over TCP/IP, without the extra layer of NetBT. For this you require TCP port 445.

To manually open a port, follow these steps:

1. Click Start, and then click My Network Places.
2. Under Network Tasks, click View Network Connections. (Or, right-click My Network Places on the desktop, and then click Properties.)
3. Right-click the connection that you use for the Internet, and then click Properties.
4. Click the Advanced tab, and then click Settings.
5. Click Add to open a new port.
6. In the Description box, type a friendly name. For example, type File Sharing : Port 445.
7. In the Name or IP address of the computer hosting this service on your network box, type 127.0.0.1.
8. In the External port and Internal port boxes, type the port number. Generally, this number is the same.
9. Click either TCP or UDP, and then click OK.