Archive for August, 2010

Installation of SSH on 64bit Windows 7 to tunnel RDP

August 26, 2010

This post covers two scenarios.

Scenario one

With this setup I have a Windows 7 VM (the server) on the same network segment as the client PC which will be taking over any work I would normally do on my Windows XP box.
My existing XP box is used for any development that is easier to do on a Windows machine than a *nix machine.
Mostly .Net development.

Scenario two

Includes tunneling to a NATed Windows 7 machine on a different network

Access to my existing Windows XP box:
Is by way of RDP session tunneled through SSH.
SSH link being established from one of my Debian eeepc’s (The computer I use most of the time) to the existing Windows XP machine.

Used OpenSSH for the existing Windows XP machine. which is no longer supported.
Couldn’t get key pair authentication working though when I set it up.

I thought I’d give OpenSSH a try on the Windows 7 machine and see how far we could get.
Once followed all directions in the ssh readme.txt and comparing with the setup on my existing Windows XP box.
The OpenSSH Server service wouldn’t start.
Followed directions here.
Tried everything I could think of and still couldn’t get the service to start.

So going on some others advise, decided to give copSSH a try, as it is an implementation of OpenSSH, but currently being maintained.
Thanks to Tevfik Karag├╝lle.
This worked out well and was a very easy setup.
The version of CopSSH used for this was 4.1.0 from here.

Initial sites used for copSSH install

Installation of copSSH

When you add a user to the CopSSH Control Panel, make sure you run the CopSSH Control Panel as an administrator (probably best to runas administrator for any actions),
else the user appears to be added, but when you try to SSH to the server, you get something along the lines of…
Unable to authenticate
Failed password for invalid user

Setup for the tunnel

Create a file in your ~ dir. TunnelToWin7Box for example, and put the following command in it.

ssh -v -f -L 3391:localhost:3389 -N MyUserName@MyWindows7Box

Turn the executable bit on.
Make sure owner and group is correct.

chmod 750 TunnelToWin7Box
chown MyUserName:MyGroupName TunnelToWin7Box

Add a command drawer to the task bar.
Add a Custom Application Launcher to the drawer that points to the TunnelToWin7Box file.
You can even add an image that makes sense to the drawer.
Mine looks like this, with 3 command launchers…

The first port there can be any port not currently in use.
The second port is the port that RDP listens on in Windows.
You also need to add an inbound rule to open port 22 or a port of your choosing on the Windows Firewall.
Also close the Remote Desktop port TCP 3389 on the Windows box.
If the server you are trying to tunnel to is behind a NAT and not on your network, I.E. you are trying to tunnel to your work machine from home for example, There is a little more involved in setting up the firewall rule and a change to the sshd_config.
You’ll need to add an inbound rule. I called it SSH. In the Programs and Services tab… selected “All programs that meet the specified conditions”.
For the Service Settings, only one that would work was “Apply to services only”. I thought it would be best to select only the ssh service, but this wouldn’t allow SSH in.
General tab just had Enabled on. Computers tab was untouched. Users and Scope was untouched. Advanced tab only needed to select Private check box.
“Protocols and ports” tab Protocol type is TCP, Local port is port 22, Remote port is All Ports.
Edit the C:\Program Files (x86)\ICW\etc\sshd_config as an administrator.
Add the line… GatewayPorts yes
Or uncomment it and set to yes rather than no if it already exists.

Command I used for the NATed scenario

ssh -v -f -L 3392:localhost:3389 -N -p 2222

The port is the port that your network admin has setup for you to forward to the machine you want to tunnel to.

When I run the command to try establish the tunnel I was getting an error message.
I made a post here.
So I un-installed copSSH and re-installed a few times trying different things.
Before last un-install, I removed the users that copSSH adds, because it doesn’t remove them on un-install,
and deleted the OpenSSHServer service using the “sc delete OpenSSHServer” command in cmd.exe shell running as administrator.
Installed again using all defaults.
It appears as even though SSH gives the message that it won’t tunnel, if you then try and open the port forwarded RDP session, it works.
In saying that, sometimes it didn’t work.
This happens if you click the command launcher more than once and you end up with more than one tunnel established.
In which case you just kill one of them and your away laughing.

Setup your Remote Desktop Session now

I’ve been using Gnome-RDP for my RDP sessions.
Set the session up to look like this.

Once done, click Connect, and you should have your RDP session from your Linux box to your Windows 7 box secured courtesy of SSH

Setup Key pair authentication

On Debian epc, or any other Debian machine for that matter

Copy the existing public key I used for SSHing to other servers to MyWindows7Box.
This is considerably more difficult if you want to scp the key to a NATed machine on another network.
Read the likes of this if your interested.
It’s the public key, so sniffing it is not such a big deal.

scp ~/.ssh/ MyUserName@MyWindows7Box:

Make sure you have the Colan at the end of the above command, else the file won’t be copied.
You may receive a prompt that the authenticity of the server you are trying to scp to can’t be established and you want to continue.
The server you are trying to connect to is added to the list of known hosts on the local machine.
Thats /home/MyUserName/.ssh/known_hosts
I didn’t get that with scp’ing to MyWindows7Box because my known_hosts already knew about MyWindows7Box from my previous OpenSSH install.

On MyWindows7Box

In the dir C:\Program Files (x86)\ICW\home\MyUserName\.ssh\
I copied the authorized_keys file to authorized_keys-OrigWithInstall (rename).
Wasn’t allowed to edit the authorized_keys file for some reason, so opened a Bash shell that comes with copSSH
and edited ~/.ssh/authorized_keys with nano. Deleting the public key.
When I tried to open this file in file explorer, it didn’t appear to have been edited.
This is because the file I thought I had edited (C:\Program Files (x86)\ICW\home\MyUserName\.ssh\authorized_keys)
was actually C:\Users\MyUserName\AppData\Local\VirtualStore\Program Files (x86)\ICW\home\MyUserName

From C:\Program Files (x86)\ICW\home\MyUserName\.ssh (or at least what I thought was there),
the public key needs to be put into the list of authorized clients that may connect to the ssh daemon.
Can do this using the Bash shell that comes with copSSH.

$ cat >> .ssh/authorized_keys

You can now delete the on the target machine.

Copied C:\Users\MyUserName\AppData\Local\VirtualStore\Program Files (x86)\ICW\home\MyUserName\authorized_keys
to C:\Program Files (x86)\ICW\home\MyUserName\.ssh\authorized_keys

With scenario two, there were a few differences.
I’m thinking some of which were probably due to a more recent version of CopSSH (4.1.0).
For starters there was no authorized_keys file anywhere, so I created one (in C:\Program Files (x86)\ICW\home\User\.ssh).
As stated above, it’s considerably more difficult to scp the from a remote pc to a NATed server.
Put in C:\Program Files (x86)\ICW\home\User\.ssh along with the authorized_keys I created, and from the bash shell
(accessible from the Copssh folder in the start menu) who’s root dir is C:\Program Files (x86)\ICW\
ran the cat command shown above.

This is probably a better way to copy the public key:

ssh-copy-id MyUserName@MyWindows7Box

Anapnea showed me this.

Could now connect via key pair auth

Made the usual changes to C:\Program Files (x86)\ICW\etc\sshd_config on MyWindows7Box

I.E. turn root access off, password auth off,
AllowUsers MyUserName
Although this is done by the CopSSH Control Panel in version 4.1.0
I think a service restart is required to reload changes.
When you make changes to the sshd_config, you’ll need to do them as an administrator (similar to how you would on a *nix system as root).
This site has example of setting up SSH to be even more secure by modifying the sshd_config.
It’s specific to copSSH.
There are many items on the net that show and describe the options when it comes to the sshd_config.
The available options are in the man page