Why is there no error message when ChunkVNC cannot connect?

[Heinzi]

We are using ChunkVNC to remotely support customers. They download the customized InstantSupport client and tell us the displayed number over the phone.

So far, so good. Sometimes, InstantSupport fails to establish a connection to the repeater, usually due to firewall restrictions on the customer's side. I can detect this by the customer's number not showing in the repeater's log.

Howerver, on the customer's side, everything looks "normal". No error message "Could not connect to repeater.example.com:443", just the big, friendly number. This makes it a bit hard to argue to the customer that the problem lies on *their* side, and that *their* local IT guy must have a look at that.

What's the reason for not showing an error message to the customer? And can I change this behaviour?

[supercoe]

When InstantSupport runs it will try to make a socket connection to the repeater's server port using the WAN address, if that fails it will try the LAN address.
If it fails to make a connection it will present the message "Connection to the repeater was not possible." and exit.
You can replicate this behaviour by running InstantSupport with the repeater closed.

Now that doesn't stop software firewalls from pausing the outgoing connection and requiring user intervention before allowing the connection.

Could you let me know which firewall software seems to be giving you the trouble?

ChunkVNC compiles itself from source code, anything is possible as far as changing its behavior, just have a peek at the InstantSupport.au3 file.

[Heinzi]

Thanks for your quick answer (and thanks for this great product, by the way!)

I tried to reproduce the issue in-house by just stopping the repeater[1] - same problem, no error message shown (even after a few minutes).

Then I tried to debug the issue. Apparently, InstantSupport is waiting for InstantSupportVNC to pop up a window indicating the the connection has failed:

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	; If UltraVNC can't connect to the repeater with the WAN address then try the LAN address otherwise exit.
	If WinExists( "Initiate Connection" ) Then

So I tried to start InstantSupportVNC.exe manually to see if it would show such a window:

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InstantSupportVNC.exe -autoreconnect ID:123456 -connect our.repeater.server:443 -run

But it doesn't. The process just keeps running, waiting to be killed.

Did I miss something obvious?

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[1] After shutting down the repeater, connections to its port fail almost instantly on the network level, so it's not a problem of a delayed connection:

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C:\>telnet our.repeater.server 443
Connecting To our.repeater.server...Could not open connection to the host, on port 443: Connect failed

[supercoe]

InstantSupport does check for UltraVNC to error out but before it even starts the VNC server it will makes it's own socket connection to the Repeater...

[Heinzi]

I tried to find this section in the code and failed... until I realized that this was a change in v3.3 and we are still using v3.2.

Trying the new version, thanks for your help!

[supercoe]

Well that explains it! I hope the latest version works out for you.

On a side note, tomorrow it will be 2 years since 3.2 came out, what a ride.