Outgoing port of UltraVNC SC ?

[cpschnuffel]

Hi there,
I frequently use UltraVNC SC for remote service purposes on its default port 5500. I'm absolutely satisfied with SC, but there's one customer who has a very strong firewall which seems to block all suspicious outgoing connections, so SC has no chance to work. The customer's PC on which SC runs is able to connect to the internet via browser, so I think port 80 and perhaps port 443 should be open. My question is:

- How does such an outgoing firewall work? Does it monitor the DESTINATION ports (i.e. my incoming port, in this case 5500) and block those outgoing connections who are suspicious to him OR does it monitor the SOURCE ports (i.e. the customer's outgoing port, in this case ... I don't know) and does its job?

- If so: what source port does SC use? Is it a fixed port, always the destination port (i.e. 5500) or is this port dynamically selected by the OS?

Every hint is highly appreciated!

Regards from Berlin/Germany
cpschnuffel

[JDaus]

- How does such an outgoing firewall work? Does it monitor the DESTINATION ports (i.e. my incoming port, in this case 5500) and block those outgoing connections who are suspicious to him OR does it monitor the SOURCE ports (i.e. the customer's outgoing port, in this case ... I don't know) and does its job?

Its really dependant upon the firewall in use, but most just look at the destination port, with some/many of those checking to see if it is http traffic, not just normal traffic ... so changing the port to 443 may work ... or it may not.

if you find that using the port 443 for viewer port doesn't work, try using SCIII with an SSL repeater ... that should get around the problem !

are you sure its a firewall or is it a proxy working on the clients site ...

- If so: what source port does SC use? Is it a fixed port, always the destination port (i.e. 5500) or is this port dynamically selected by the OS?

Not sure, but most apps are usually dynamic (including IE and firefox). so i doubt it will be locked down to source port ...

if you fail to get through with any of the above solutions, you may want to look at 'vnc2me sc' which uses ssh tunneling (you can change the default ssh server port to 443, and most firewalls and proxies allow it through - except IIS - )

hope this helps

[cpschnuffel]

Hi JDaus,
I assume it's both - an outgoing firewall AND a proxy at the customer's site .

I will check if vnc2me sc fixes the problem and will afterwards give you a reply...

Thanks so far,
cpschnuffel