[Q] Using port 80 and firewalls
pteeson "at" rogers.com
Thu Jun 6 21:45:02 2002
On Thursday, June 6, 2002, at 03:44 AM, Beerse, Corni wrote:
>> However I know that port 80 is open for sure and also port 21. Probably
>> port 443 is also open.
> And are they free or are they in use?
> What protocol is open? vnc needs tcp, not udp.
I understand that vnc uses tcp and not udp.
As to whether the ports are in use. I am doing this testing on my own
There are two machines: Win98SE and WINNT4.0SP5.
In doing the test neither machine was running either a browser or an ftp
So in that sense they were not in use. Is that what you meant?
Thus I make the assumption that I should be able to use those ports
since the only traffic on them would be the vnc packets.
>> In the viewer I entered 192.168.100.127:-5820 as per the
>> docn but the Win98SE keeps getting an GPF.
> Try (2^16 - 5820) or (2^32 - 5820) for portnumbers.
> You have a working, not-firewall connection: try this port change on
> machine to see if your setup works from the vnc site.
Interestingly enough when I run VNC on the 98SE either as an app or as a
service and then check the properties I see that the display number
shown is 4,294,961,476.
This turns out to be 2^32 - 5819. Curious.
However no matter what I enter at the listener (on the NT box) I get a
GPF on the 98SE machine.
I havn't tried the other way (NT as vnc and 98Se asviewer) because the
world in which I will have to live uses 98SE.
So I need to get it working that way round.
>> Now I'm a Mac programmer who is even less than a white belt
>> on Windows
>> so I would really appreciate some help here on how to solve the
>> problem - namely connecting to a Win98SE box that is behind a
>> firewall with only ports 80, 21, and 443 available to me.
> Bad luck message: if those ports are the only open ports, they are most
> likely to be in use:
> port 21: ftp
> port 80: http
> port 443: https
See my comments above when I am testing on my LAN.
Nothing else is using those ports. No browser; no ftp.
> From my point of view, you can best use port 21 as it is useless without
> port 20 since ftp uses both ports, one for controll (21) and one for
> Debugging a vnc connection from the viewer side: telnet to the machine
> the proper port (in netscape: telnet://machine:port/) should give a "RFB
> xxx.xxx" message. Start doing this at the vncserver machine:
> telnet://localhost:port/ or telnet://127.0.0.1:21/ then, on the same
> machine, use the real IP address.
I'll give this a try. But I may have to end up reading the source code
to try and figure out what is or is not happening.