[LUAU] Resent from luau at hoku.net: From: <jching at flex.com>

[Mike Ballon]

Kind of long but....

Q. Will VNC work through a firewall?
A. It depends on your firewall, and whether you want to access a server
inside your firewall from elsewhere, or a server outside your firewall from
inside.
Generally firewalls are designed to prevent incoming connections except to
certain well-known machines and ports.  If you can configure these to
include your VNC server, then you will be able to access it from anywhere in
the world.  There is a good argument to be made for the fact that VNC is
less of a security risk than X, so if your site doesn't allow X in or out it
may still allow VNC.
Many modern firewalls will allow outgoing connections initiated from inside,
so you can often access servers on outside machines.  It is straightforward,
for example, to recompile the viewer source to include SOCKS support, or to
make other special arrangements. See the contribs page.
It's a pity that Java within a browser doesn't automatically use SOCKS if
the browser is configured to use it.  There's probably Java SOCKS support
out there somewhere...
If your internet access is through a router which does Network Address
Translation, you may be able to configure the router to redirect particular
incoming ports to particular machines. So you could run WinVNC with a
display number of 0 on machine snoopy, and with display 1 on machine
woodstock, then set your router to send port 5900 to snoopy and 5901 to
woodstock.  See below for information on the other port numbers used by VNC.

Q. Which TCP/IP ports does VNC use?
A. VNC server listens on two ports. The exact port numbers depend on the VNC
display number, because a single machine may run multiple servers. The most
important one is 59xx, where xx is the display number.  The VNC protocol
itself runs over this port. So for most PC servers, the port will be 5900,
because they use display 0 by default.
In addition, VNC servers normally have a small and very restricted web
server built in, which allows you to connect a browser to them and use the
Java viewer.  This runs on port 58xx.  Note that this is the HTTP port used
for downloading pages and applets, but once the applet is running it uses
59xx for VNC just like any other viewer.
The servers can be changed to listen on other ports if, for any reason,
these are not suitable for you.  See the server's documentation for more
details.  Most of the viewers, if given a display number larger than 99,
will interpret it as a direct port number and will not add 5900.
If you are running a viewer in 'listening' mode, where it accepts
connections initiated by the server, it will listen for incoming VNC on port
5500.  It's unlikely that this will apply to you, because the servers we
distribute publicly don't have this facility.

----- Original Message -----
From: Chris Wong <wongc at hoku.net>
To: <luau at luau.hi.net>
Sent: Friday, March 19, 1999 7:18 PM
Subject: [LUAU] Resent from luau at hoku.net: From: <jching at flex.com>


> Subject: Access to computers behind firewalls
>
> Hi all,
>
> I'm wondering if anyone knows if it is possible to login to a computer
> behind a firewall and run X applications.  I have programs like ssh, and
> VNC.  But I don't know how to get access to the computer behind the
> firewall.
>
> Any help is greatly appreciated.
>
> --jc
> --
> Jimen Ching (WH6BRR)      jching at flex.com     wh6brr at uhm.ampr.org
>
>
> --
>      __   __  __________  __
>     / /  / / / / __  / / / /  Home Page: http://luau.hi.net
>    / /__/ /_/ / /_/ / /_/ /
>   /____/\____/_/ /_/\____/  LUAU - Linux Users AnonymoUs - Hawaii
>
>    To unsubscribe: echo unsubscribe luau | mail majordomo at luau.hi.net
>            LUAU meetings are the 3rd Tuesday of each month 6pm

--
     __   __  __________  __
    / /  / / / / __  / / / /  Home Page: http://luau.hi.net
   / /__/ /_/ / /_/ / /_/ /
  /____/\____/_/ /_/\____/  LUAU - Linux Users AnonymoUs - Hawaii

   To unsubscribe: echo unsubscribe luau | mail majordomo at luau.hi.net
           LUAU meetings are the 3rd Tuesday of each month 6pm