maemo.org - Talk - wiki: logging into a linux pc using VNC and SSH

maemo.org - Talk (https://talk.maemo.org/index.php)

- General (https://talk.maemo.org/forumdisplay.php?f=7)

- - wiki: logging into a linux pc using VNC and SSH (https://talk.maemo.org/showthread.php?t=14743)

wiki: logging into a linux pc using VNC and SSH

I just posted a first draft how-to on the wiki explaining a way to connect to a pc running (Ubuntu) linux from a Internet Tablet using TightVNC and SSH. It is meant for people with basic knowledge of the commandline. Feel free to add any improvements.

Re: wiki: logging into a linux pc using VNC and SSH

Here's how I do just the opposite (logging into n800 from Ubuntu via VNC tunnelled through ssh):

Needed:
- x11vnc installed on n800
- vnc password file, placed in /home/user/.vnc/passwd, created on Ubuntu using vncpasswd and copied to n800

Code:

ssh -t -n -L 5903:localhost:5900 n800 'x11vnc -localhost -rfbauth .vnc/passwd -display :0' &

sleep 3

vncviewer -encodings 'copyrect tight zrle hextile' localhost:3

Re: wiki: logging into a linux pc using VNC and SSH

Hi,

EDIT this post is obsolete, all problems solved and solution posted in the wiki:
http://www.internettablettalk.com/wi...ng_VNC_and_SSH

I use VNC over ssh with my N810 connecting to a computer running Ubuntu 7.10 with its standard VNC server.

On the ubuntu computer I first installed openssh-server (which then runs as a service at every reboot).

On my tablet (OS2008, chinook) I installed the openssh-client from https://garage.maemo.org/projects/openssh/

Using X Terminal on my N810 I connect via

Code:

ssh -X -l username-at-remote-computer ip-address-or-dyndns-of-remote-computer

Still in X Terminal i use

Code:

vncviewer localhost

or better

Code:

vncviewer localhost -fullscreen

to get the remote desktop.

But:
for the login screen of vncviewer I can't use the N810's virtual keyboard

also, when using the hardware keyboard, I can't use uppercase or numbers in the password (meaning: all ciphers requiring the caps or Fn keys can't be used for VNC passwords)

thus I have to set a password containing only lowercase letters on the VNC server side (the Ubuntu computer)

after login I still don't have uppercase letters or numbers available for the keyboard.

after successful login, vncviewer crashes very often when it has finished drawing the remote desktop for the first time - seems to be a problem of the vncviewer on the N810 (error message contains s.th. with TXscrollbar and void)

vncviewer options like "-noauto" and "-encodings" are not recognized by the vncviewer on the N810

therefore I have to set the encodings an color levels via the vncviewer popup-menu (available when pressing the "-" button of the N810).

as the "-" button is used for the popup-menu and the "+" button acts as "F7", there is no way to get a right-mouse-click as advertised in the release notes of vncviewer...

vncviewer crashes often (segmentation faults etc.)

But apart from these "minor-problems" I'm still glad to have VNC on my N810 at all. :D

Cheers

Franko30

Re: wiki: logging into a linux pc using VNC and SSH

Quote:

Originally Posted by Franko30 (Post 126276)

Still in X Terminal i use

Code:

vncviewer localhost

Hi,

sorry I have to quote myself - but I forgot s.th. in the previous post:

When starting VNCviewer from the application launcher for connections within my local network, everything works as stated in its release notes ("+" and "-" buttons for right and middle mouseclick).

So the question is:
How can I use my ssl-connection invoked via X Terminal with VNCviewer started via the application launcher?

Thanks in advance

Franko30

Re: wiki: logging into a linux pc using VNC and SSH

Quote:

Originally Posted by Franko30 (Post 126677)

So the question is:
How can I use my ssl-connection invoked via X Terminal with VNCviewer started via the application launcher?

Franko30

I haven't tried all the other options you mentioned. I only tested the way described in the wiki running a n800+os2008 (version 50-2) and a dell laptop running Ubuntu Feisty and it works flawlessly.

VNC and SSH with x11vnc

Hi again,

Today I tried several possibilities to use VNC via ssh but none of those already described here (and in the wiki) works for me.

Using trial and error, I found out the following:

Ubuntu's integrated VNC-Server sucks, as it doesn't support the display options (:0, :1 etc).
TightVNC server doesn't display the desktop of the user currently logged in. It creates another virtual desktopy for the remote user, see http://www.tightvnc.com/vncserver.1.html. That's not suitable for me, as I want to control the applications I already started when I logged in as a desktop user before I left the house.
Therefore I decided to use the x11vnc server with SSH, which worked right from the start and has everything I need (meaning: it works and has tons of options)!

Howto use x11vnc with an N810 running OS2008 (example: Ubuntu 7.10 machine as host, Nokia tablet as client):

Install the openssh-server package on the Ubuntu machine.
Openssh-server wil be started automatically at every login.
Install the x11vnc server package on the Ubuntu machine. Start it with the "-setpasswd" option to set a VNC password.
Then start the x11vnc server on the Ubuntu machine with this command:

Code:

x11vnc -usepw -forever -display :0 -loop -solid darkblue -skip_dups -speeds dsl

The options explained:
"-usepw" is needed to actually use the password you set earlier
"-forever" is needed so x11vnc doesn't shutdown after every VNC session which would be its default behaviour;
"-display :0" tells the x11vnc server to use display 0 so you can use port 5900 - display 1 would use port 5901;
"-loop" should create an external loop process that is supposed to restart x11vnc in case of a crash;
"-solid darkblue" sets a monochrome desktop background (good for slow connections);
"-skip_dups" is needed because every keyboard button I pressed on the N810 appeared twice on the Ubuntu machine (seems to be a bug) and skip_dups supresses that;
"-speeds dsl" is a preset to deal with latency issues, use "-speeds modem" for slower connections.
All options are explained (in great detail) in the manual, accessible via "man x11vnc" on the Ubuntu machine.
Make sure x11vnc showed port 5900 in the last lines of all its messages after the start, so that later in the SSH connection you can actually forward the right port. If it showed 5901, use that number for the SSH connection.
Login from remote using the Nokia's openssh client "ssh" in X Terminal. The command is

Code:

ssh -X -l username IP-address -L 5900:localhost:5900

where "username" is the username-on-the-Ubuntu-machine and "IP-address" is the IP-or-dyndns-address-of-the-Ubuntu-machine's-Internet-access. The "-L" option forwards the localhost connections to the port 5900 (display 0 of the VNC-server) to the remote client via SSH. This is a trick to use VNCviewer on the Nokia tablet with the "localhost" option. I got that from another VNC tutorial here: http://www.cl.cam.ac.uk/research/dtg...nc/sshvnc.html The "-X" option enables the usage of GUI programs on the remote tablet - for example to use Firefox or Gimp remotely. :D
Start the tablet's VNCviewer via the application launcher and enter "localhost:0" as host address, also enter the password set in x11vnc. If you had to change the port options for the SSH connection you might need to use "localhost:1" or similar.
Do whatever you want to do on the remote Ubuntu machine, then exit VNCviewer and don't forget to stop the SSH connection on your tablet by typing "exit" in X Terminal.

Important notice!

When using SSH, only the actual SSH tunnel is secure. Remember that you have to open a port on the firewall of your local Ubuntu machine (or its Internet gateway).
Therefore thousands of script kiddies can try to gain root access via SSH on your Ubuntu machine the moment you open the ports on your firewall.
To prevent this, you need to block SSH Brute Force Attacks and disable SSH root access. This is explained on the following web pages:

Using-pam-to-block-brute-force-attacks

Protecting Linux against automated attackers

Keeping SSH access secure
the most important thing is:
"PermitRootLogin no" in the /etc/ssh/sshd_config file

I'm going to put the x11vnc stuff and the articles about securing ssh in two Wiki articles - but not tonight, it's getting kind of late...

Cheers

Franko30

Re: wiki: logging into a linux pc using VNC and SSH

Hi Frank. One of the reasons I prefer tightvnc over x11vnc is that with tightvnc you can set the screen dimensions with the -geometry argument to match the n800. With x11vnc you are forced to use the screen dimensions of the existing session and end up ith scrollbars around the screen, and slowness because of the extra screen information being sent. Do you know if the geometry can be set somehow?

Re: wiki: logging into a linux pc using VNC and SSH

Quote:

Originally Posted by iamthewalrus (Post 127045)

Do you know if the geometry can be set somehow?

No, not yet. But the screen can be scaled on the server side - meaning, you can define the screen size sent via VNC to be x% of the Original. But blurring is possible, as with all scaling processes.

Maybe there's another option in the man pages I didn't recognize as being "geometry relevant".

A question to you:

What do you use tightvnc for, when all it does is create a new virtual desktop for the remote connection.

Is there any possibility at all to gain access to the desktop of the user currently logged in (and therefore control already opened applications like video recording software and such)?

Cheers

Franko30

Re: wiki: logging into a linux pc using VNC and SSH

Quote:

Originally Posted by Franko30 (Post 127240)

What do you use tightvnc for, when all it does is create a new virtual desktop for the remote connection.

Mainly to use apps that are not ported to maemo, and to access my documents.

Quote:

Originally Posted by Franko30 (Post 127240)

Is there any possibility at all to gain access to the desktop of the user currently logged in (and therefore control already opened applications like video recording software and such)?

Don't know, sorry. But since the application is running under the same username, only a different session, I would think that you should be able to send at least commands to it.

Re: wiki: logging into a linux pc using VNC and SSH

Quote:

Originally Posted by iamthewalrus (Post 127267)

But since the application is running under the same username, only a different session, I would think that you should be able to send at least commands to it.

Sorry, not possible: It's a video-recorder software written in Java that I have to access. I have to use its GUI :(

So, I'll stick with my x11vnc setup.

Thanks anyway.

Franko30