Putty SSH Port Forwarding

Putty SSH Port Forwarding

Postby clahti » 2009-10-28 22:05

Hello all:

I am setting up secure VNC access to three remote computers behind a firewall using SSH. For example the private IPs of the three machines are:

192.168.111.101
192.168.111.102
192.168.111.103

I have setup the following NAT through the firewall:

<PUBLIC-IP>:22:192.168.111.101

so essentially calls to the public IP on port 22 are forwarded to the first machine, which also has cygwin OpenSSH server listening. I then use an SSH client to connect to that machine, no problems and works as expected. I then setup the following SSH tunnels in the SSH client:

15901:192.168.111.101:5900
15902:192.168.111.102:5900
15903:192.168.111.103:5900

Connecting UltraVNC Viewer to localhost:15902 and localhost localhost:15903 work exactly as expected and I can access these two via the SSH tunnels. The problem however is attempting to connect to localhost:15901 which does not work at all. The first error was "Loopback connections are disabled", so I enabled loopback connections in the configuration. Now the error is "Connection Failed, Error reading Protocol Version". All three are setup exactly the same way and testing among the three on the local network works fine. I am guessing there is a problem with the loopback because this is the system with the SSH NAT forward. Interestingly if I setup the following tunnels for Microsoft Remote Desktop:

13901:192.168.111.101:3389
13902:192.168.111.102:3389
13903:192.168.111.103:3389

then all three remote desktop sessions work perfectly, but I really wish to use VNC. Am I missing something? NAT forward of port 5900 is not possible unfortunately.

This is being setup for our engineering staff so I am trying to keep things very simple, and I have done this many times for both windows and linux hosts using realvnc with no issues, but UltraVNC has the built in file transfer which I want the eng staff to use without having to launch a separate SCP client.
clahti
 
Posts: 2
Joined: 2009-10-28 21:44

Re: Putty SSH Port Forwarding

Postby JDaus » 2009-10-29 00:31

clahti wrote:15901:192.168.111.101:5900

try using
Code: Select all
15901:127.0.0.1:5900
instead of the local IP ... as sometimes systems don't like using the real IP for loopback (have come accross this for several other systems ... never tried to setup UVNC to use anything other then loopback when doing a loopback ...

let us know how you go ...
ask a silly question and remain a fool for 5 minutes...
don't ask, and remain a fool for life - JDaus 2003

without imperfections, neither you nor i would exist - Steven Hawkins
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Location: Sydney, Australia

Re: Putty SSH Port Forwarding

Postby clahti » 2009-10-29 21:32

JDaus wrote:
clahti wrote:15901:192.168.111.101:5900

try using
Code: Select all
15901:127.0.0.1:5900
instead of the local IP ... as sometimes systems don't like using the real IP for loopback (have come accross this for several other systems ... never tried to setup UVNC to use anything other then loopback when doing a loopback ...

let us know how you go ...


Thanks for the response, unfortunately I have the same problem. I recall that version 1.0.2 did not have this problem.
clahti
 
Posts: 2
Joined: 2009-10-28 21:44


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