No remote access?

John Roland Elliott John_Roland_Elliott "at"
Fri, 28 Sep 2001 01:18:37 +0000

<<responses interspersed>>

From: "Gregg Waltz" <getsome831 "at">
To: <vnc-list "at">
Cc: <John_Roland_Elliott "at">
Sent: Thursday, September 27, 2001 4:42 PM

> To: vnc-list "at"
> Cc: John_Roland_Elliott "at"
> Subject: >
> 1)  Yes, i am using the address on the WAN side of my firewall and yes, my
> RT314 does NAT between a private network and a single public address.
> also successfully setup the port forwarding previously w/ an ftp server,
> dcc sends, etc.

Sorry to have to ask that one ... never can tell what might get overlooked.

> 2)  Let's see here:
> -  I don't think i can put a computer on the unprotected (WAN) side of the
> firewall, by defualt my routeer forces everthing behind the firewall.

I thought you might connect the WAN side of the router (hub or crossover
cable may be needed here) to another computer running VNC viewer to see if
it could get through your home firewall but it seems like you've concluded
that it's not a problem with the firewall.

> -  I put my PC directly on the net w/o the router/firewall and i still got
> "ReadExact: Socket error while reading." error message.  So i guess it's
> my firewall.
> 3)  We actually use VNC at my work on multiple computers on our network so
> i'm pretty sure that port isn't being blocked.

Okay that shows that VNC works *inside* the network at work but there's
still the question whether port 5900 is allowed out through the firewall
that protects your network at work from the bad guys. Do you know of any VNC
servers outside your network that you can reach from inside your network?

> As for changing the VNC server listening port, i'm not exactly sure about
how i'd go about that.

Sadly, you have to change the registry entries for the server and enter some
bogus stuff in the client's server field. I'll paste some relevant
discussion at the end of this message.

> Any other comments/questions that might lead me anywhere?
> thanks,

Don't thank me 'til it's working.

> -gregg

A thread from the discussion group about changing the port used by VNC to

First of all, the big number is right:

2^32 - 5900 + 21 = 4294961417

Second, to my surprise, the VNC server control panel would not accept it for
me either; it behaved just like you said.

Using regedit, you can enter the port number directly without any of the
arithmetic. The keys/values you want are:


The PortNumber value, 15, is hexadecimal for 21 which you can enter as 21
when you use regedit. As a sanity check, after you enter these, you will see
that the VNC server properties show 4294961417 for the display number.


----- Original Message -----
From: "FOO JOUNG WEE" <foo.joungwee "at">
To: <vnc-list "at">
Sent: Wednesday, September 26, 2001 3:43 AM
Subject: RE: Changing negative port number to VNC server

> Hi Andrew,
> I did as you told, changing the port number to 4294961417. But VNC server
> seem to recognise this large number. After I clicked "Apply" & "OK", when
> re-open the properties, the port number is reset back to zero. Do you know
> to overcome this problem?
> Regards,
> Jon
> I think I know what you want to do. The trick is that the port number is
> internally represented an signed 32 bit number, so can be represented in
> a two's complement manner. Change the port number to the equivalent
> large decimal number.
> -5879 is FFFF E909 which is 4294961417
> Andrew
> -----Original Message-----
> From: owner-vnc-list "at"
> [mailto:owner-vnc-list "at"] On Behalf Of FOO JOUNG WEE
> Sent: Wednesday, 26 September 2001 12:12
> To: vnc-list "at"
> Subject: Changing negative port number to VNC server
> Hi. I want to use port 21 as the port for VNC server. But I am unable to
> change the port number to -5879. I can only key in positive port number.
> However at the VNC viewer, I'm able to change it to -5879 (5900 - 5879 =
> 21). I've serched the FAQ and documentation and couldn't find anything
> on this issue. Can anyone please help me? Thank you.
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