NetBIOS Over TCP/IP

Microsoft Windows, in its default state, uses TCP/IP, and NetBIOS Over TCP/IP, for networking. Sometimes, we forget this detail. NetBT is so easily overlooked, yet it is essential.

If we are looking at the output from “ipconfig /all”, and we see

        IP Address. . . . . . . . . . . . : 192.168.1.50
        Subnet Mask . . . . . . . . . . . : 255.255.255.0
        Default Gateway . . . . . . . . . : 192.168.1.1
        DHCP Server . . . . . . . . . . . : 192.168.1.1
        DNS Servers . . . . . . . . . . . : 192.168.1.11
                                            192.168.1.33
        NetBIOS over Tcpip. . . . . . . . : Disabled
        Lease Obtained. . . . . . . . . . : Wednesday, April 16, 2003 11:19:12
        Lease Expires . . . . . . . . . . : Wednesday, April 23, 2003 11:19:12

Obviously, we’re going to correct that. But what if we simply see

        IP Address. . . . . . . . . . . . : 192.168.1.50
        Subnet Mask . . . . . . . . . . . : 255.255.255.0
        Default Gateway . . . . . . . . . : 192.168.1.1
        DHCP Server . . . . . . . . . . . : 192.168.1.1
        DNS Servers . . . . . . . . . . . : 192.168.1.11
                                            192.168.1.33
        Lease Obtained. . . . . . . . . . : Wednesday, April 16, 2003 11:19:12
        Lease Expires . . . . . . . . . . : Wednesday, April 23, 2003 11:19:12

Do we see any problem there? Probably not. Look in the TCP/IP Properties wizard, under Advanced – WINS. There are 3 possible settings for NetBIOS Over TCP/IP

  • Default.
  • Enable.
  • Disable.

The last setting, Disable, becomes apparent when we see the first example above. But what if if we see the second example above? Well, that display can result from either the “Default”, or the “Enable” setting. If it’s not showing Disabled, it could be either.

The Default setting, according to the wizard, is for

Use NetBIOS setting from the DHCP server.

If your LAN

  • Has a domain.
  • Has computers running only Windows 2000, Windows 2002 (aka Windows XP), and Windows 2003 (aka Server 2003).
  • Uses DNS, properly setup, for name resolution.

then you may wish to disable NetBT, and use direct hosted SMBs.

But what if your LAN has a NAT router providing DHCP services, and / or has no domain? NAT routers have no setting for NetBIOS Over TCP/IP. So, if you select “Default”, and you have a NAT router, what result do you get? If NetBT is not enabled, you have 2 possibilities.

  • If the server that you’re trying to access supports direct hosted SMBs, your client computer should connect.
  • If the server does not support direct hosted SMBs, then your client computer won’t connect. You’ll get an Error 53, most likely.

I know of several cases where folks asking for help have had strange problems with name resolution, or with file sharing access, that couldn’t be explained by Firewall Problems, or any other simple scenario.

In many cases, all that is needed is to explicitly set NetBIOS Over TCP/IP to “Enable”.

You know when you need NetBT in your network. So why not make sure that it’s configured? Don’t settle for Default; Enable it. In the TCP/IP Properties wizard for each network connection,

  • Hit the Advanced button.
  • Select the WINS tab.
  • Select the radio button “Enable NetBIOS over TCP/IP”.
  • Hit OK 3 times.
  • Close Network Connections, after enabling NetBT on ALL network connections.

Be safe – don’t settle for “Default”.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s


%d bloggers like this: