Subject: Problem with Netbios

From: Maria Alandes Pradillo <[email-masked]>
Date: Mon, 28 Feb 2000 11:42:12 +0100

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    Hello!

        I am trying to share a directory of a server (WinNT) in my LAN,
which is protected by the firewall. Following Microsoft specifications,
a netbios session uses port 139. I am using plug-gw when this service is
called to connect it to the server.

        It doesn't work, could it be because I didn't set up the correct
entries in netperm-table or maybe because this protocol is more complex
and plug-gw cannot deal with it?

         I have no idea of what else I can try to share files between
the LAN and DMZ.

                                Thanks!

--
María Alandes Pradillo

Universidad Politécnica de Madrid (Madrid Technical University)
E.U. Informática. Organización y Estructura de la Información
Ctra. de Valencia, Km. 7. E-28031 Madrid. Spain
T.: (+34)-913367881 Fax. (+34)-913367520
e-mail: [email-masked]

---

From: Bill Kocik <[email-masked]>
Date: Mon, 28 Feb 2000 07:19:57 -0800

> and plug-gw cannot deal with it?

If I remember correctly, it uses port 139 but with UDP, not TCP.

-- 
Bill Kocik
Taos Mountain - "The Sys Admin Company"
Santa Clara, California
http://www.taos.com

---

From: "Nico Baggus" <[email-masked]>
Date: Mon, 28 Feb 2000 23:20:04 +0100

Netbios uses various services:

	137 UDP name service
	138 UDP datagram service
	139 TCP data xfer.

You can find more about this protocols at the samba site
http://www.samba.org/

regards,
Nico Baggus

> -----Original Message-----
> From: [email-masked]
> [mailto:[email-masked]]On
> Behalf Of Bill Kocik
> Sent: Monday, February 28, 2000 4:20 PM
> To: Maria Alandes Pradillo
> Cc: [email-masked]
> Subject: Re: Problem with Netbios
>
>
>

---

From: "Bill Kocik" <[email-masked]>
Date: Mon, 28 Feb 2000 15:10:25 -0800

> Netbios uses various services:

So I guess I didn't remember correctly. Apologies, and thanks to Nico for
pointing out my mistake.

Bill Kocik

---

From: "Tom Krotchko" <[email-masked]>
Date: Mon, 28 Feb 2000 18:13:35 -0500

It uses ports 137, 138 & 139.

137 & 138 are UDP, 139 is TCP.

If you really want to understand NetBIOS, aka SMB, I highly recommend
the two books on Samba; one is a SAMS book "Teach Yourself SAMBA",
the other...I can't remember and someone has "borrowed" it...hmmm.

Anyway, I'm sure its on Amazon.

---

From: Rick Murphy <[email-masked]>
Date: Mon, 28 Feb 2000 18:36:28 -0500

>If I remember correctly, it uses port 139 but with UDP, not TCP.

There's actually three different ports. NetBIOS session service is used for 
user authentication; when you log in to a domain, you're connecting to the 
netbios session service. TCP Port 139. The shared drive data is carried 
over NetBIOS datagram service, UDP 138. Name lookups use NetBIOS name 
service, UDP port 137.
You can't connect to a shared drive unless you permit UDP 138 and TCP 139. 
Name service isn't necessary. You can't plug nbdatagram because it's UDP; 
you can't NAT it in an simple packet filter because the prototcol contains 
imbedded IP addresses that must also be translated.

Opening NetBIOS session service can open you to a dictionary attack, 
leaving your shared directories open to the world.
         -Rick