RDP over SSH Tunnel Post: 302717853

Sponsored Content

Special Forums Cybersecurity RDP over SSH Tunnel Post 302717853 by DGPickett on Thursday 18th of October 2012 04:31:05 PM

10-18-2012

Registered User

Semantics cn cloud the issue. Every PC with RDP is a server, and the support dude has the client. The tcp client sends the first packet SYN, and if there is a listening socket, that replies with the second, reply packet SYN ACK. An ssh tunnel listens on one end of the ssh session host pair on some specified port, as a server, and forwards connections to the opposite end host to a new client socket connected to the host and port specified. So, ssh is the obvious tool, as long as one end is visible to each end. If you ssh localhost, the two middle hosts can be the same host.

Suppose on host A you "ssh -L 3389:C:3389 B", forwarding A:3389 to new client connections on B (high port) to port 3389 C, which is the target PC to be serviced port 3389. When your tech points his RDP client host D to A:3389, it will really be talking to the target PC RDP service. The RDP client D connects a socket on D:high-port to A:3389, A sends via ssh client app inside ssh connection to sshd server on B, which makes a new socket, connects it to C:3389, and everyone shuffles data flow both ways.

Security rules sometimes prevernt -L, but sometimes -R is legal, where the listening server part of the tunnel is on the sshd server end, and the new client sockets originate on the ssh client app.

Often, the problem is really simpler, and all that is not needed. A firewall E in the middle may able to see both C and D even though they cannot see each other, like if C is on the internet and D is on a 10. unroutable address. Using NAT or tcpRelay, it can listen for D and connect to C.

Now, if you want a dynamic service where many PCs can be the target, something like a web service could set up the forwarder or tunnel to the indicated host. For security, it is nice if there is a timeout and some filtering of incoming connections, so only D can temporarily get that connection to C:3389.

DGPickett

View Public Profile for DGPickett

Find all posts by DGPickett

6 More Discussions You Might Find Interesting

1. Programming

using a ssh tunnel with nx compression

hi everybody and thank you for this wondefrul forum this is my first thread posted here and i hope that i could find some help from your part (i am even sure) :D here is the situation: i am to develop an application of remote desktop access such as vnc, vpn and especially nx i want to develop...

2. UNIX for Dummies Questions & Answers

SSH tunnel working for ssh but not for sshfs

I'm trying to setup a link between my home pc (work-machine) and a server at work (tar-machine) that is behind a gateway (hop-machine) and not directly accessible. my actions: work-machine$ ssh -L 1234:tar-machine:22 hop-machine work-machine$ ssh -p 1234 user@127.0.0.1 - shh access on...

3. IP Networking

Help with SSH tunnel?

I have a Java web app on machine (X) that needs to talk to an LDAP server (Y) on :636, but the LDAP server is only accessible on a particular network. I can login to a machine (Z) on that network from X, and this machine can talk to the LDAP server on :636. How can I tunnel so that X can...

4. IP Networking

VPN ssh access over RDP port?

Guys, Can I use an open RDP port to gain ssh access to my Linux server running the other side of our firewall? I work from home on the odd occasion, we only have RDP port 3389 available once logged into the VPN. I would rather ssh into my workstation without the need for a desktop display. ...

5. Solaris

Tunnel X over ssh for 11.3

Hello Solaris experts: Trying to bring the 11.3 gdm screen over ssh to a Linux Box: I did the following: 1. made chanes to /etc/ssh/sshd_config & bounced ssh daemon: # X11 tunneling options X11Forwarding yes X11DisplayOffset 10 X11UseLocalhost yes 2. From the remote Linux box: ...

6. UNIX for Advanced & Expert Users

Tunnel using SSH

I am not clear with the part of concept of Tunneling using ssh. ssh -f -N -L 1029 192.168.1.47:25 james@192.168.1.47 I found out that above code works for me . but didn't quite well understood how ti works and need to ask you guys some questions. since we are using tunnel through ssh ...

LEARN ABOUT OPENDARWIN

ssh-keysign

ssh-keysign(1M)                                                                                                                    ssh-keysign(1M)

NAME

       ssh-keysign - ssh helper program for host-based authentication

SYNOPSIS

       ssh-keysign

       ssh-keysign  is  used  by ssh(1) to access the local host keys and generate the digital signature required during host-based authentication
       with SSH protocol version 2. This signature is of data that includes, among other items, the name of the client host and the  name  of  the
       client user.

       ssh-keysign  is  disabled  by  default and can be enabled only in the global client configuration file /etc/ssh/ssh_config by setting Host-
       basedAuthentication to yes.

       ssh-keysign is not intended to be invoked by the user, but from ssh. See ssh(1) and sshd(1M) for more information about host-based  authen-
       tication.

       /etc/ssh/ssh_config

           Controls whether ssh-keysign is enabled.

       /etc/ssh/ssh_host_dsa_key
       /etc/ssh/ssh_host_rsa_key

           These  files  contain the private parts of the host keys used to generate the digital signature. They should be owned by root, readable
           only by root, and not accessible to others. Because they are readable only by root, ssh-keysign must  be  set-uid  root  if  host-based
           authentication is used.

       ssh-keysign will not sign host-based authentication data under the following conditions:

         o  If the HostbasedAuthentication client configuration parameter is not set to yes in /etc/ssh/ssh_config. This setting cannot be overri-
            den in users' ~/.ssh/ssh_config files.

         o  If the client hostname and username in /etc/ssh/ssh_config do not match the canonical hostname of  the  client  where  ssh-keysign  is
            invoked and the name of the user invoking ssh-keysign.

       In  spite of ssh-keysign's restrictions on the contents of the host-based authentication data, there remains the ability of users to use it
       as an avenue for obtaining the client's private host keys. For this reason host-based authentication is turned off by default.

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE         |      ATTRIBUTE VALUE        |
       +-----------------------------+-----------------------------+
       |Availability                 |SUNWsshu                     |
       +-----------------------------+-----------------------------+
       |Interface Stability          |Evolving                     |
       +-----------------------------+-----------------------------+

       ssh(1), sshd(1M), ssh_config(4), attributes(5)

AUTHORS

       Markus Friedl, markus@openbsd.org

HISTORY

       ssh-keysign first appeared in Ox 3.2.

                                                                    9 Jun 2004                                                     ssh-keysign(1M)