I've been meaning to try NoMachine NX for a while. Its promise of fast remote X11 sessions sounded exactly like what I wanted to log into my work desktop remotely (I really like having a remote desktop with saved state you can just pick up from when using remote access). That was pretty much all I knew about the software, so I was a completely blank slate.

The getting started guide is the perfect example of how not to write a getting started guide.

Firstly, Section 1 - "Getting started" - gives me a full history of the product, goes into significant depth about the challenges of forwarding X11 requests, talks about the caching and compression implementation, round-trip latency measurement, the details of two-way proxying system and discusses every other feature of the software.

My eyes glazed over after about the first paragraph. That's all great -- I just want to know what to do!

At this point, I assume that I'm required to run some sort of daemon at the remote end. I download and install the server package (it is explained that the server package requires the client and agent packages as well, fine).

I'm paging down, looking for something to get me started. I'm happy to see Section 7 - "Set up your NX Server environment" (remember, at this point I though I needed some daemon running in the background constantly). It even has some commands commands to type, so I tap away, running nxserver --useradd nxtest --system. My server binary doesn't even seem to recognise these options. I give up, assuming that the server isn't running and nothing will work. The getting started guide has abruptly ended and I have no idea what to do.

As it turns out, it's all completely trivial. Here's the missing "getting started guide".

• Download and install the client, agent and server packages on the remote end. You need to have ssh access to this box.
• Install the client on your end.
• Run /usr/NX/bin/nxclient. It will start a wizard where you input the remote host name.
• The client will, under the hood, ssh to the remote end, open the tunnel it needs, start the server and do all the magic required to make things "just work". A remote desktop will appear.
• That's it!

Additional tips:

• It's easy to tunnel this connection (for example, if you have to bounce through a ssh gateway to your internal network). Do something like /usr/NX/bin/nxssh -o 'Compression=no' -L 2022:remote.host:22 -f -N user@sshgateway.company.com and then connect the client to localhost:2022. You don't want to compress this link, as NX is already doing it.
• The only way I can find to make a new session is to start nxclient with the --wizard command.
• Don't click "Disable encryption of all traffic" if you're tunneling. AFAICT this tries to redirect the client to a non-encrypted port, which obviously won't get through.

Other than the documentation, it really works as promised, making remote X11 usable. One really nice feature is that it is smart about the resolution of the remote desktop, filling up your local screen. Add to that you don't need anything setup but your normal ssh connection, and it's a great remote desktop solution.

posted at: Wed, 04 Feb 2009 15:10 | in /linux/tips | permalink | add comment (11 others)

#include <stdio.h>
#include <unistd.h>
#include <alloca.h>
#include <string.h>

int main (void)
{
        size_t n = confstr (_CS_GNU_LIBC_VERSION, NULL, 0);
        if (n > 0)
        {
                char *buf = alloca (n);
                confstr (_CS_GNU_LIBC_VERSION, buf, n);
                printf("%s\n", buf);
        }
        return 0;
}

$ /lib/libc.so.6
GNU C Library stable release version 2.7, by Roland McGrath et al.
Copyright (C) 2007 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.
Compiled by GNU CC version 4.3.1 20080523 (prerelease).
Compiled on a Linux >>2.6.24.4<< system on 2008-06-02.
Available extensions:
	crypt add-on version 2.1 by Michael Glad and others
	GNU Libidn by Simon Josefsson
	Native POSIX Threads Library by Ulrich Drepper et al
	BIND-8.2.3-T5B
For bug reporting instructions, please see:
<http://www.gnu.org/software/libc/bugs.html>.

$ LD_DEBUG=help ls
Valid options for the LD_DEBUG environment variable are:

  libs        display library search paths
  reloc       display relocation processing
  files       display progress for input file
  symbols     display symbol table processing
  bindings    display information about symbol binding
  versions    display version dependencies
  all         all previous options combined
  statistics  display relocation statistics
  unused      determined unused DSOs
  help        display this help message and exit

To direct the debugging output into a file instead of standard output
a filename can be specified using the LD_DEBUG_OUTPUT environment variable.

xtightvncviewer*popupButtonCount: 11

xtightvncviewer*popup*button9.label: Alt-F1
xtightvncviewer*popup*button9.translations: #override\n\
                                            <Btn1Down>,<Btn1Up>: \
                                            SendRFBEvent(keydown,Alt_L) \
                                            SendRFBEvent(keydown,F1) \
                                            SendRFBEvent(keyup, F1) \
                                            SendRFBEvent(keyup, Alt_L)

xtightvncviewer*popup*button10.label: Alt-F2
xtightvncviewer*popup*button10.translations: #override\n\
                                            <Btn1Down>,<Btn1Up>: \
                                            SendRFBEvent(keydown,Alt_L) \
                                            SendRFBEvent(keydown,F2) \
                                            SendRFBEvent(keyup, F2) \
                                            SendRFBEvent(keyup, Alt_L)

xtightvncviewer*popup*button11.label: Alt-F12
xtightvncviewer*popup*button11.translations: #override\n\
                                            <Btn1Down>,<Btn1Up>: \
                                            SendRFBEvent(keydown,Alt_L) \
                                            SendRFBEvent(keydown,F12) \

ssh -M -S /tmp/vncssh-firewall.ctl -L 2022:desktop.internal.company.com:22 -f -N username@firewall.company.com
ssh -M -S /tmp/vncssh-localhost.ctl -N -p 2022 -L 5901:localhost:5901 -f -N username@localhost
xtightvncviewer -encodings tight localhost:1
ssh -S /tmp/vncssh-firewall.ctl -O exit localhost
ssh -S /tmp/vncssh-localhost.ctl -O exit firewall.company.com

all: final

.PHONY: prepare clean

final: prepare
        # run build process

prepare: prepare-phase1-stamp prepare-phase2-stamp

prepare-phase1-stamp:
        # untar data or something
        touch $@

prepare-phase2-stamp: prepare-phase1-stamp
        # run a script or do something else
        touch $@

clean:
        rm -f *-stamp

#! /bin/sh -e

case "$1" in
  start)
    echo -n "Starting ssmtp tunnel "
    start-stop-daemon --start --quiet --exec /usr/sbin/stunnel -- -c -d ssmtp -r securemail.internode.on.net:ssmtp
    echo "stunnel."
    ;;
  stop)
    echo -n "Stopping ssmtp tunnel "
    start-stop-daemon --stop --quiet --oknodo --retry 2 --exec /usr/sbin/stunnel
    echo "stunnel."
    ;;
  restart)
    $0 stop
    sleep 1
    $0 start
    ;;
  *)
    echo "Usage: /etc/init.d/ssmtp-tunnel {start|stop|restart|reload|force-reload}"
    exit 1
esac

exit 0