Samba Tunneling
From Beakstar Wiki
Contents |
Sharing (tunneling) Samba/CIFS/SMB file systems over SSH
Without disabling local file sharing
Edwin Olson, eolson@mit.edu, 5/5/2003
This article's original source is here: http://www.blisstonia.com/eolson/notes/smboverssh.php
I no longer need to tunnel samba over ssh, so I no longer use these instructions. While they once worked for me, I have no idea if they would currently work, given new software versions and patches.
Introduction
Suppose you have a samba server on server S, and wish to connect to it from a machine C. Perhaps you can't connect directly, because either S can't open port 139, or because you don't trust the security of windows file sharing. (Both are good reasons!)
Cast of characters:
- S: The samba server you want to connect to. In my case, a linux machine running samba.
- C: The client machine from which you want to access S. In my case, a Windows XP machine.
The "simple" solution is to disable file sharing on system C and ssh to S, forwarding port 139 via the ssh connection. Then you can connect to your remote samba share by connecting to "\\localhost". You must disable local file sharing, otherwise it will use port 139, making it impossible for you to tunnel another machine to that port. Unfortunately, Windows will not let you specify a port number for an SMB server; it always uses port 139. So forwarding a remote smb server to a local port other than 139 doesn't get you anywhere. Grumble!
The goal of this page is to help you access files on S from machine C without disabling file sharing on C. The same technique can be used (albeit tediously) to mount an arbitrary number of remote file systems via ssh.
Briefly, our approach is to add virtual network adapters to machine C, so that machine C can have more than one port 139. Our real interface will continue to have local file sharing running, but each virtual interface can be used as the end of an ssh tunnel. For example, we can create a virtual ethernet adapter with a IP address of 10.0.0.1, and forward S:139 to 10.0.0.1:139. This clever idea originally comes from http://lists.samba.org/archive/samba/2004-May/085358.html. I've tried to document what worked for me, which was *slightly* different than what they suggested.
Update: The method, as described, does not work on WinXP SP2 unless you install the (official) Microsoft patch available here: http://support.microsoft.com/?id=884020. Please note that I have not personally tested this patch. Thanks to Salem Derisavi for pointing out this solution!
The method
We start by configuring Putty, a free ssh client that supports port forwarding. I've received a report that old versions of putty may not work, but that versions newer than 0.56 are fine.
- Download and install Putty, a very decent and free ssh client, onto C.
- Fire up Putty on C, create a new connection to S. Make sure you can ssh from C to S before going any further.
- Configure a new SSH tunnel for the connection you created in the previous step.
- Source port=10.0.0.1:139 (the IP:port notation is wider than the text box, but it will work!)
- Destination=127.0.0.1:139 (this tells the server to connect the other end of the tunnel to the server's port 139.) Previous versions of these instructions suggested S's actual IP address, which might not work if S doesn't know its own true IP address (due to NATing, for example.)
- Click add, save the connection
We'll give your computer an additional (fake) IP address, and we'll port forward to that address instead of the computer's real IP. Windows XP will continue to do file sharing on the real IP address. We'll assign it an IP of 10.0.0.1 (that's what we configured putty to use above.)
- System->Control Panel->Add Hardware
- Yes, Hardware is already connected
- Add a new hardware device (at bottom of list)
- Install the hardware that I manually select
- Network adapters
- Microsoft , Microsoft Loopback Adapter
- (Go through the installation procedure.)
Now we configure the new localhost adapter.
- Open up your existing (real) ethernet adapter and write down your gateway and DNS server addresses.
- Open your new fake ethernet adapter (Network Connections) , enter a made-up IP address (I suggest 10.0.0.1, which is a privately routable address that most folk don't use.)
- Enable Client for Microsoft Networks.
- Disable File and Printer Sharing for Microsoft Networks
- Enable Interent Protocol (TCP/IP)
- Click on properties for TCP/IP.
- Enter your chosen IP address (10.0.0.1), subnet mask (255.255.255.0), and gateway and DNS information you got from your real adapter.
- Under advanced->WINS, Enable LMHosts Lookup and Disable NetBIOS over TCP/IP
At this point I had to reboot; it didn't tell me to, but it wasn't working.
Now we test out our connection:
- Start->run
- type: "\\10.0.0.1".
- You should be greeted by your samba share!
When things go wrong
- Did you reboot?
- Is putty running and forwarding ports?
- Are your forwarded connections working correctly? (I set up a port forwarding on port 80 as a sanity check: if I could point mozilla at http://10.0.0.1 and get my server's web server, I know that putty/port forwarding is working.)
- Make sure your samba server is properly configured (did you add C to your hosts allow in smb.conf?)
- Try telnetting to 10.0.0.1 139 from a command shell on C. Do you get a connection? If it doesn't connect, then either samba or port forwarding is bonked.
- Using XP SP2? Make sure to check out Microsoft's knowledgebase article listed here: http://support.microsoft.com/?id=884020.
If I've missed something, give me a yell.
Hints from others
Others have tried this and emailed me hints and troubleshooting information. I have not verified this information, but I archive it here in the hope that some of it may be useful to you. Robert S writes:
I was recently unable to get this to work on a work PC - until I upgraded PuTTY. It might be worth pointing out that this does not work with older versions of PuTTY, even though they allow port forwarding. It certainly works with version 0.56.
I am using PuTTY with PowerMenu, which allows you to send the PuTTY window to the system tray. A good way of avoiding desktop clutter. You can download it at http://www.veridicus.com/tummy/programming/powermenu.
Andrew Beck writes:
It seems that microsoft networking attempts to use directory services over port 445. If this fails it then attempts to use port 139. Firstly you need to stop port 445 being bound by windows (google gives options). Personally I use my firewall to block outgoing connections on 445. It also appears that if there are no valid interfaces with netbios over tcp enabled, then windows will not attempt to use port 139. If you are using dialup (which doesn't have this option) and don't have a lan connected, chances are samba over ssh won't work.
The work around: Add a second loopback adapter with some IP address. Enable netbios over TCP on this adapter. You never actually use this adapter but it's presence causes windows to fall back to port 139 on the loopback being used for ssh fowarding. It is bizarre, but it works!
Sam Samdi writes:
Although things didn't initially work for me, the following did (and might be worth adding to your page, if you feel it is appropriate)
With the loopback adaptor: I disabled Client for MS Networks and removed the gateway IP from the TCP/IP setup.
With my SSH clients: Putty - for the remote machine I put the WAN/internet IP address (127.0.0.1 didn't work).
OpenSSH (Cygwin SSH) - in the SSH config file (../home/user/.ssh/config) I put the following lines:
LocalForward 139 wanserver:139 GatewayPorts yes
(wanserver is my server's WAN/internet IP; GatewayPorts allows the client to tunnel from all loopback adaptors - 10.0.0.1 as well as 127.0.0.1)
