NetBIOS Datagram?

NetBIOS Datagram?

Post by Tim the Bake » Mon, 02 Apr 2001 05:32:00



I've been getting this alert in ZAPro for the last couple of days.

"The firewall has blocked Internet access to your computer (NetBIOS
Datagram) from 209.53.xxx.xxx (NetBIOS Datagram).
Occurred: 4 times between 3/31/2001 10:39:54 and 3/31/2001 11:16:32"

Today I've had around 20 of these. Thursday, there were over 100. I've
let my ISP know, as the IP address belongs to one of their customers
(cable internet), but I am curious as to what a NetBIOS Datagram is.
Can anybody clue me in?

Thanks

tim

 
 
 

NetBIOS Datagram?

Post by Barf » Mon, 02 Apr 2001 08:24:07


It's used with Microsoft Networking (NetBIOS over TCP/IP - NBT). It's fairly common. Don't let it in or out. You can safely block ports 135-139 without any problems (on a NetBEUI network).

FAQ: Firewalls: What am I seeing?: http://packetstorm.securify.com/papers/firewall/firewall-seen.htm
RFC Sourcebook: http://www.networksorcery.com/enp/default0204.htm
GRC/Shields UP!: https://grc.com/x/ne.dll?bh0bkyd2

Mike
-  -


> I've been getting this alert in ZAPro for the last couple of days.

> "The firewall has blocked Internet access to your computer (NetBIOS
> Datagram) from 209.53.xxx.xxx (NetBIOS Datagram).
> Occurred: 4 times between 3/31/2001 10:39:54 and 3/31/2001 11:16:32"

> Today I've had around 20 of these. Thursday, there were over 100. I've
> let my ISP know, as the IP address belongs to one of their customers
> (cable internet), but I am curious as to what a NetBIOS Datagram is.
> Can anybody clue me in?

> Thanks

> tim


 
 
 

1. NetBIOS Datagram?

So, every time I send of receive mail I get an alert in ZAP that the mail
server is trying to access my computer.
"The firewall has blocked Internet access to your computer (NetBIOS
Datagram) from 207.153.185.194 (NetBIOS Datagram)"
It is trying to access me on port 138. Is this ok? I thought that netbios
was part of my LAN and not to be exposed to the outside internet (I have
a DSL connection and 4 computers here at home on a LAN). I do know the
address is that of my ISP's mail server and I wouldn't mind including it
in my trusted sites, if it would make the mail move faster or something
like that. Is there a reason that I wouldn't want to do that?
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