If anybody cares...
OSI layer 5 can't move across a network. It must be carried by layer 4 who
is carried by layer 3, etc.
In this case, Layer 3 is IP, layer 4 is TCP, layer 5 is NetBIOS.
NetBIOS is technically a session level protocol and thus is always
transported by something else. Originally, this was netbeui or ipx/spx.
Later, it became NetBT, aka, netbios over tcp/ip.
=========================
Paul H. Gracy
[EMAIL PROTECTED]
phone: 404 705 2873
#include <std.disclaimer>
=========================
> -----Original Message-----
> From: Lance Ecklesdafer [SMTP:[EMAIL PROTECTED]]
> Sent: Thursday, April 08, 1999 8:01 PM
> To: Kafil Din; Christopher J. Witter
> Cc: pdmallya; [EMAIL PROTECTED]
> Subject: Re: Netbios
>
> I am given to understand that NETBIOS is itself not a protocol at all.
> NETBEUI is a very fast and efficient protocol, but it is not routable and
> does not scale. For a small network like most small offices and small
> businesses, this is one of the fastest protocols available. In order to be
> able to scale and support backwards compatibility along comes NBT. This
> protocol allows NETBIOS calls from workstations and servers to traverse a
> network with more than one physical segment. Layer 3 devices will forward
> NBT packets and you can also configure most layer 3 devices to forward
> broadcast traffic for functions like DHCP and WINS.
>
> In Cisco, this is the helper address when configuring IP interfaces.
>
> Just MHO ...
>
> Lance.
>
>
> Lance Ecklesdafer, CNP
> Senior Network Engineer
> re:Sources, Inc.
> [EMAIL PROTECTED]
> http://members.tripod.com/ecklesd
> "My God ... It's full of stars"
>
>
> -----Original Message-----
> From: Kafil Din <[EMAIL PROTECTED]>
> To: Christopher J. Witter <[EMAIL PROTECTED]>
> Cc: pdmallya <[EMAIL PROTECTED]>; [EMAIL PROTECTED]
> <[EMAIL PROTECTED]>
> Date: Thursday, April 08, 1999 12:22 AM
> Subject: Re: Netbios
>
>
> >
> >
> >
> >NetBIOS itself certainly can't be routed but they will be using NBT which
> >is NetBIOS encapsulated in IP. This certainly can be routed and is how
> >they have been passing NetBIOS around on IP networks for years.
> >
> >If you are using NT DNS in the picture and have Enable DNS for WINS
> >resolution turned on you can actually resolve NetBIOS names to IP
> >addresses.
> >
> >Provided your firewal does not allow inbound connection and the
> >userid/password used to connect to the external share is not one you use
> >internally then you should not have an exposure.
> >
> >Kafil.
> >
> >
> >
> >
> >
> >"Christopher J. Witter" <[EMAIL PROTECTED]> on 08/04/99 03:16:27
> >
> >
> >To: pdmallya <[EMAIL PROTECTED]>
> >cc: [EMAIL PROTECTED]
> >Subject: Re: Netbios
> >
> >
> >
> >
> >Netbios can't be routed so unless you are using a VPN to bridge the two
> >networks together than and they are then on the same IP subnet then this
> >isn't possible.
> >
> >Christopher Witter
> >MCSE, MCP +Internet, ICIS, IIAE
> >
> >Windows NT Crashed.
> >I am the Blue Screen of Death.
> >No one hears your screams.
> >
> >On Wed, 7 Apr 1999, pdmallya wrote:
> >
> >> Hi,
> >>
> >> A department in my company wants to permit PC's in our network to
> access
> >> files in machines on an external network using Netbios file-sharing.
> I'm
> >> being told that this does not open any loopholes in our security,
> >because:
> >> (a) we can connect our network to the external one using a Checkpoint
> >> Firewall, with a rule permitting NBT connections from our internal PCs
> to
> >> the external machines containing the files. There will be no rule
> >permitting
> >> a reverse connection.
> >> (b) there will be no shared disks on our network, and the Checkpoint
> >rules
> >> will enforce this.
> >> (c) ergo, our network is not exposed in any way.
> >>
> >> I am not quite convinced - can anyone give me some more information or
> >> pointers on this?
> >>
> >> TIA & Regards
> >>
> >> Prabhakar D. Mallya
> >>
> >>
> >> -
> >> [To unsubscribe, send mail to [EMAIL PROTECTED] with
> >> "unsubscribe firewalls" in the body of the message.]
> >>
> >
> >-
> >[To unsubscribe, send mail to [EMAIL PROTECTED] with
> >"unsubscribe firewalls" in the body of the message.]
> >
> >
> >
> >
> >
> >
> >-
> >[To unsubscribe, send mail to [EMAIL PROTECTED] with
> >"unsubscribe firewalls" in the body of the message.]
> >
>
>
> -
> [To unsubscribe, send mail to [EMAIL PROTECTED] with
> "unsubscribe firewalls" in the body of the message.]
-
[To unsubscribe, send mail to [EMAIL PROTECTED] with
"unsubscribe firewalls" in the body of the message.]
