wishlist: vnc framebuffer device?

wishlist: vnc framebuffer device?

[Harald Dunkel]

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Hi folks,

To make a headless system "less headless", would it be possible
to integrate a vnc framebuffer device into the kernel?

The idea is to have a vnc server instead of a local screen and
keyboard to show the boot output and to provide a console login
on /dev/tty{1..6}. It would be pretty similar to qemu. No need
for fancy graphics, of course. The IP address might either be
obtained using DHCP, or it might use an IP address/netmask
given on the kernel command line.

I understand that authentication might be an issue here.

Hopefully this isn't one of the oh-no-not-again questions. I
haven't seen it mentioned on the kernel or linux-console
mailing lists before.


Regards

Harri
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Re: wishlist: vnc framebuffer device?

[Veyrdite]

Hey Harald,

 > To make a headless system "less headless", would it be possible
 > to integrate a vnc framebuffer device into the kernel?

VNC as I understand is more suitable for graphical environments.  For
just text SSH or even telnet/netcat would be more practical.

 > The idea is to have a vnc server instead of a local screen and
 > keyboard to show the boot output and to provide a console login
 > on /dev/tty{1..6}. It would be pretty similar to qemu. No need
 > for fancy graphics, of course. The IP address might either be
 > obtained using DHCP, or it might use an IP address/netmask
 > given on the kernel command line.

As I understand it most init implementations log all of their messages
to a file in /var/log, so you can view them all post-bootup once you
have vnc'd or into the box.  This would be the simplest and most
foolproof solution, but may not be what you want.

If you are going to send your messaged over a trusted LAN or network
( ie not the internet ) then I'd go with the 'netconsole' module for the
kernel.

See https://www.kernel.org/doc/Documentation/networking/netconsole.txt

It (hopefully) would just require an extra kernel command line on the
headless machine and a 'netcat -ul portnumber' on the receiving machine.
  'Hopefully' because I am unsure if your kern

The problem is that everything is sent as unencrypted plaintext.

 > I understand that authentication might be an issue here.

Yes, if you mean the security of the transmitted data.

It is unlikely your ISP and other routing companies will violate your
security, but there is always a risk of someone doing something they
shouldn't be.  It is also *very* unhackerlike to send any plaintext over
the internet, and you should be secretly ashamed deep down if you do so.

If you do need to secure this information, it might be possible to link
SSH to your innitab and have things sent that way.  That is idealistic.

In the worst case scenario, you will just have to write a script that
acts as an init service that delays all bootup until it can make an SSH
connection to another computer and shove the lines of bootup information
from /var/log to the other computer as they appear.

If my words have gone over your head, please tell me.  I have no clue
what you skill level and experience is, and I am making assumptions :)

Regards, William

Re: wishlist: vnc framebuffer device?

[richard -rw- weinberger]

On Sat, Jun 16, 2012 at 1:05 PM, Harald Dunkel <harri@afaics.de> wrote:
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>
> Hi folks,
>
> To make a headless system "less headless", would it be possible
> to integrate a vnc framebuffer device into the kernel?

What about a VNC server which exports a framebuffer device?
Like: http://code.google.com/p/android-vnc

No need to implement VNC in kernel space.

-- 
Thanks,
//richard

Re: wishlist: vnc framebuffer device?

[Harald Dunkel]

Hi Richard,

On 06/17/12 12:13, richard -rw- weinberger wrote:
> 
> What about a VNC server which exports a framebuffer device?
> Like: http://code.google.com/p/android-vnc
> 
> No need to implement VNC in kernel space.
> 

If it can run in user space, then thats fine with me. But I
would guess the pseudo framebuffer device itself (without the
networking, authentication and encryption stuff) has to
reside in the kernel.

It is very important to me to get access to the VNC console
very early in the boot procedure, e.g. if there is a fsck
asking for help, or if a badly configured root device drops
me on busybox.

For qemu/kvm hosts (and others) it is very convenient to
access the console via VNC. For "real" hosts I am restricted
to SOL or some remote management hardware module providing
a web interface.

It would be very nice to get an improvement here.


Regards

Harri

Re: wishlist: vnc framebuffer device?

[richard -rw- weinberger]

On Mon, Jun 18, 2012 at 8:59 AM, Harald Dunkel <harald.dunkel@aixigo.de> wrote:
> It is very important to me to get access to the VNC console
> very early in the boot procedure, e.g. if there is a fsck
> asking for help, or if a badly configured root device drops
> me on busybox.

Start the VNC server in your initrd and make sure that it gets
not killed... :-)

-- 
Thanks,
//richard