Stupid subnetting question

[ammo]

Originally posted here by cgkanchi
Plus, since I've disabled NetBIOS over TCP/IP, no one outside the lan can access my share anyway.

cgkanchi, are you using Win2k/XP or 95/98?

You see, there are only 3 (basic) ways of accessing windows shares (SMB is the actual protocl name for the "data transfer"):
- NetBEUI: network level protocol extension to NetBIOS, not routable so needs to be on the same network (ethernet) segment and has nothing to do with IP addressing.
- NetBIOS over TCP/IP: Access is made through a TCP/IP (network & transport layers)connection over ports 137-139, with NetBIOS for what could be called session layer.
- SMB over TCP/IP: Starting with Win2k, windows can exchange SMB directly over TCP without the need for a NetBIOS interface. This is done over tcp port 445.

So, if you were using NetBEUI (which I don't beleive you are), your sharing would either have worked automatically at first (meaning you're on the same ethernet segment) or never at all (you're not on the same segment and there's nothing you can do about it since NetBEUI is not routable).

Because you have mentionned using UNC paths with an IP address (\\10.0.0.X), it means you are either using NetBIOS over TCP/IP or SMB over TCP/IP, but then again, since you say you have disabled NetBIOS over TCP, this only leaves SMB over TCP.

Now my actual point here is that unless there's a firewall blocking tcp 445 in front of this lan, your shares ARE accessible from outside the lan when using SMB over TCP, just as much as with NetBIOS over TCP.


Ammo

[cgkanchi]

Plus, since I've disabled NetBIOS over TCP/IP, no one outside the lan can access my share anyway.

Crap! I meant SMB over TCP/IP. It was really late and I didn't know what I was typing. Anyway, what I meant was that I have a software firewall blocking access to port 445. Anyway, since I'm behind a hardware firewall/router (Red Hat 9 running IPTables that my ISP has setup for the whole network with I.P. of 10.0.0.1) accessing my computer from the net using an inbound connection is pretty much impossible anyway.

Cheers,
cgkanchi

[Faqt]

We happen to be working on subnetting at school....seeing as how I'm so new to the concepts I really can't add much to the conversation, but I do have a couple of links that might help you to understand where the subnet mask comes from.

http://www.ralphb.net/IPSubnet/index.html

http://www.learntosubnet.com/