I have LAN witch connected to Internet through ADSL router and I have run file sharing in the LAN.

I want to access my file sharing by another location in the Internet and i know this is not the way to connect file sharing through internet and i can use FTP or remote desktop to inside LAN computer and i know it is not safe to share files in the web but my questions are :

1- Is there any way i can use feature like port forwarding through router to connect individual computer in the LAN ?

2- How can i access that Sharing with a program from outside the LAN ?

3- Does NetBIOS protocol work through internet ?

  • lets say i cant use another way or change anything except port forwarding on the router , can i able to access my shared files ?

lets answer your questions in reverse:

  1. NetBIOS itself is not a routable protocol, so in its native state, no it cannot travel the internet. using NetBIOS over TCP/IP, you can route it however.
  2. a client like sambaclient (linux) is required to access the share. most windows and linux distros have the client built in.
  3. yes, you can forward tcp/137-139 and UDP/445 (and udp/389 if you are using active directory)

all that said, this is a really really really bad idea. make sure you lock down all the administrative shares, as many clients ignore teh $ rule for hidden shares, and if an attacker gets access to IPC$ or ADMIN$, you are toast.

  • NetBIOS itself is just an API, not a real protocol. It's unroutable when run over NBF, but routable over IPX or TCP/IP (NBT). – user1686 Mar 28 '13 at 16:02

NetBIOS-over-TCP/IP can work over the Internet – mostly: see the part about NBNS below.

For file sharing, Windows uses the SMB protocol.

  • Modern versions of Windows use SMB directly over TCP over TCP port 445.

  • Traditionally, SMB was used over NetBIOS Session Service. These days NetBIOS runs over TCP/IP (aka NetBT) and works over the Internet, using TCP port 139.

  • For Windows to work properly, ICMP Ping should be allowed as well.

  • Note that you cannot change the ports when connecting from other Windows computers; you must use ports 445 and 139. This means that you can only access one computer over the Internet directly.

What does not work is the NetBIOS Name Service, which relies on broadcasts – UDP port 137 when using TCP/IP, for example. Even if you forwarded this in your router, it still wouldn't work. However, the Name Service is not needed for file sharing to work. You can use DNS in its place, or just enter the IP address directly: e.g. \\\public-files.

Keep in mind that exposing SMB and/or NetBIOS to the Internet can be horribly insecure. There is no data encryption at all, the authentication protocol is weak against sniffers, and the Windows SMB/NetBIOS implementation has had many security holes in the past. Avoid doing this – set up a VPN instead.

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