VNC session drops...Can't re-establish connection

[croessus]

I can successfully connect to another computer for roughly 15 minutes and then I'll no longer be able to control the other machine. It seems to freeze. My session will then terminate. I'll try to re-establish the connection but it will no longer prompt for the password and after several minutes will fail. The only way to reconnect is to have the machine remote machine reboot. Again after roughly 15 minutes the session will do the same thing. The remote machine is using a 2wire router with port forwarding setup and the Windows XP firewall has been configured to allow UVNC. Any ideas would be greatly appreciated.

[mattice06082]

Can you Log debug infos to the WinVNC.log file to see if that provides you any additional information that might help debug. It's an option under that Admin Properties (double-click on the eyeball icon). It sounds like you internet connection is dropping out.

[richardstevenhack]

This is exactly the same problem I've run into just tonight, after several weeks of perfectly good UltraVNC use.

I am running UltraVNC on Windows XP Pro with SP2 and all updates.

I have recently installed the AOL Kaspersky AV. The other day I installed the Comodo firewall - which I suspect is the cause of the problem.

My setup is that I run UltraVNC over the Hamachi VPN to connect to a client's office and remote control their desktops. I am also using the Repeater to control other UltraVNC servers in the client's network and this has worked fine for me. This has worked fine for several weeks now with no problems, except when the client machine that Hamachi connects to is down, of course. It was down Sunday evening and I was unable to connect. Today, since the staff are back to work, I expected the machine to be up, and it was, so I started working on it this evening.

I try to connect using Hamachi, and I am able to open a shared folder with no problem. I then connect with UltraVNC and begin working on the desktop. After about ten minutes or so, the connection freezes, and then the Viewer closes or crashes. At this point, if I try to open the Hamachi connection, it won't open, and UltraVNC will not connect.

If I "power off" the Hamachi VPN and "power on" the VPN again, it re-establishes the Hamachi connection and I am able to open a shared folder on the client machine. However, the UltraVNC connection remains dead. The viewer comes up, I try to connect, it starts negotiating the protocol and goes nowhere until I kill it.

If I reboot the machine, I can then use Hamachi and UltraVNC again as normal, until again after about ten or fifteen minutes the Viewer window freezes and crashes. This was repeated several times. It seems to be time related for some reason.

Then after one such experiment, I rebooted and UltraVNC will not connect at all now.

I uninstalled the Comodo Firewall and reinstalled the previous Kerio Personal Firewall V2.1.5.

UltraVNC still will not connect.

I uninstalled and reinstalled UltraVNC, retaining the same encryption key in the directory that was used to connect to the client machine. UltraVNC even after reinstallation will still not connect any more at all.

I don't know whether the client machine connection is somehow messed up until I go down there tomorrow and check it out, and see if I can connect from the client machine to the UltraVNC server on my machine.

But for now I'm dead in the water, which is very bad because I need to be doing remote support for this client.

I have the suspicion that somehow something in the Windows Registry connected with the TCP/IP stack has been hosed so that now UltraVNC simply won't work anymore on my machine. I've seen this nonsense before on Windows XP, where the networking is about as fragile as a reed.

When I reinstalled UltraVNC, I DID have a problem getting rid of the service. I had to boot into safe mode and uninstall it from there, because the service hung shutting down, and then remained in a "stopping" state and couldn't be removed outside of Safe Mode. Is it possible that I need to take further steps to uninstall UltraVNC again completely and then reinstall?

When I reinstalled UltraVNC, I always tell it to clean out old registry keys, so I don't think that is the issue.

Anybody have any ideas what I can do to shake this loose and make UltraVNC work again?

[SuperTurtle]

The interesting part is that right after I experienced the loss of connection, I tried to launch my browser, and it could NOT connect.

About 2-5 minutes later, I could re-connect.

My high speed is reliable…dead reliable. It generally goes for a year, or more without troubles.

Yet, on Monday, 3 times while using single click, I lost my internet connection. Note I am running the viewer (it my clients are running SC). I thought it was perhaps my ISP killing the connection. The reason why my ISP would do this because the terms of agreement do NOT allow me to run a web server on this connection. And, for maximum compatibility and success for Single-Click, I have the *incoming* connection on port 80 (that means SC is going out on port 80..which is usually open – even on corporate systems).

So, I gave my ISP a support phone call, and they ASSURED me that they were NOT re-setting my connection due to a incoming port 80. So, scratch my ISP as being the bad guy here.

However, how could my internet connection STOP WORKING 3 times during the day, and exactly the same time that I was using the vnc viewer???

After the 1st failure on Monday, I just thought...ok, bad ISP. The 2nd time the vnc stopped, I launched my browser right away (and, it could NOT connect). I also hit send/receive in my email client (outlook). BOTH STOPPED WORKING. (however, other computers on the same network DID NOT experiance a stoppage).

My email would not work, nor my IE7 browser. So, the loss of this connection is not just VNC. (I suggest all of you test this concept/idea NEXT TIME when vnc stops working). What this hints towards is a re-set, or damage to the tc/ip connection for the WHOLE computer…NOT just vnc.

However, this break in connection ONLY occurs when using VNC!!!

In about 2-3 minutes..the conenciton came back....

Another point is that I also have ports forwarded through my router. The original poster here mentioned this port forwarded (I don’t think it is significant, but certainly worth mentioning until we figure out what is going on).

So, there is many of us experience this problem…we just have not been able to re-produce this (until then, we stand in ridicule until we can prove this).

One thing I have not yet tried is to simply disable the windows firewall. I have a meeting tomorrow morning with the same client that went down 3 times on Monday (very embarrassing while trying to do a demo). I going to turn off my windows fire wall. I actually keeping my fingers crossed that I do NOT have a problem. (because then I have solution!!!).

Also, because it is a important meeting, I also setup a paid commeral system as backup (www.copilot.com). I have the back system ready since I can’t have another embarrassing failure like I did on Monday. (the demo was being done in a corporate board room…and everyone had to be called from their desks. The failure happened 3 times…and each time…everyone went back to their desks to work…and then ½ hour later…I had them all come back to the board room…this happened 3 times, and 3 times I lost my connection complete. By the way, did I mention I been using SC for about 2 years now without a problem.

Like all of you here, I *know* there is something going on that is causing this…I just can’t put my finger on what it is….

So, first thing: when the connection drops…test you internet connection (can you launch ie, or do a send/receive in outlook). If you all experiencing a loss of connection in the internet stack on your computer…then it is NOT you ISP..but something going on with VNC….

Super Turtle

[bevtech]

I am not disagreeing something is going on but if it was the single click application causing this wouldn't you have this problem more frequently??

Or even Ultra VNC for that matter. Any kind of packet loss will cause UVNC to drop or hang. Single click will mostly reset iself in 5 min. Ultra VNC may take alot longer to reset.


3 disconnects on the same day really is not proving anything sadly. Those are the hardest to reproduce and isolate. Need to have an error.


Other issues that maybe causing this would be a dyndns host resetting or lossing connectivity for a few minutes. This would cause your other pcs to stil be responding and yet your vnc to fail..


Also you mentioned a board room so I would also wonder if the coperate network would have anything to do with your tcp/ip resets and locking your stack on your pc

[SuperTurtle]

I am not disagreeing something is going on but if it was the single click application causing this wouldn't you have this problem more frequently??

Yes but it actually the vnc viewer on my end that stopping. So, I did not want to miss-direct any idea, or concept that SC is the problem here. I don’t think it is…

Any kind of packet loss will cause UVNC to drop or hang. Single click will mostly reset iself in 5 min. Ultra VNC may take alot longer to reset.

Yes, I think the above is what is going on. The ONLY strange part here is that when the vnc viewer stopped, my all of the tc/ip connections halted…so, that is the only fishy part here. (again, I stress I am only running vncviewer).

3 disconnects on the same day really is not proving anything sadly. Those are the hardest to reproduce and isolate. Need to have an error.

I totally agree. However, the fact of my connection being “broken” on my end is the strange part. So, perhaps a pack error, or retry of some type is freezing up winvnc. When looking for the smoking gun, 3 failures is NOTHING to write home about. However, 3 failures in which all other tc/ip services fail at the same time IS SOMETHING to write home about.

Other issues that maybe causing this would be a dyndns host resetting or lossing connectivity for a few minutes. This would cause your other pcs to stil be responding and yet your vnc to fail..

Perhaps, I am using a ip number for the connection, and not using any name resolution of any type.

Also you mentioned a board room so I would also wonder if the coperate network would have anything to do with your tcp/ip resets and locking your stack on your pc

Yes, again I agree 100%. However, “they” were on the corporate network, NOT ME!!!

So, yes..some type of system that re-sets, or disables their connection to stop a connection is possible. As mentioned, I having them make a outgoing connection on port 80. While the port is obviously open (else they could not use their browsers), it is most certainly possible that their firewalls is sophisticated, and STOPS CERTAIN KINDS of traffic, and does not just restrict open ports.

However, as mentioned, I doing the demo from my home, and using my ISP for my internet connection (I not using a vpn, or THEIR network). So, why would re-set on the corporate side kill ALL OF MY connectively. Why would my browser and email stop?

That is why I asked the others in this thread to next time RIGHT AWAY LAUNCH their browser or email, ..and test if they have connectivity. I lost complete internet connection 3 times at exactly he SAME TIME (well, about 20 seconds into the vnc session) in one day. That is not a coincidence.

It is possible that a bad packet complete freezes up all tc/ip services…is a known issue?

Super Turtle

[bevtech]

Yes, again I agree 100%. However, “they” were on the corporate network, NOT ME!!!

wait maybe a miss communication here did all 3 attempts happen when you are on there corperate lan or did some of them happen when you are on your lan?? I have seen sonicwalls completey halt traffic on a vnc connection very quickly..

So, yes..some type of system that re-sets, or disables their connection to stop a connection is possible. As mentioned, I having them make a outgoing connection on port 80. While the port is obviously open (else they could not use their browsers), it is most certainly possible that their firewalls is sophisticated, and STOPS CERTAIN KINDS of traffic, and does not just restrict open ports.[/quotes]

That would be my guess that there firewalls due deep packet inspection and realize that the info it not a html request

However, as mentioned, I doing the demo from my home, and using my ISP for my internet connection (I not using a vpn, or THEIR network). So, why would re-set on the corporate side kill ALL OF MY connectively. Why would my browser and email stop?

Let me see if i am understanding you. Your server drop the connection to your home which you were accessing from a coperate lan connection.. if there firewall quit sending the packets while your home pc was waiting form them it might cause a tcp/ip stack lock or crash. It should not but it is possible..

That is why I asked the others in this thread to next time RIGHT AWAY LAUNCH their browser or email, ..and test if they have connectivity. I lost complete internet connection 3 times at exactly he SAME TIME (well, about 20 seconds into the vnc session) in one day. That is not a conductance.

I agree it this is an excellent post and hope that an answer is found.

Being behind a coperate firewall on either a sever or viewer may cause unusual problems..

It I possible that a bad packet complete freezes up all tc/ip services…is a known issue?

Bad packet is one thing but a stop packet during an active connection is another problem all together..

I have seen ultravnc do this exact some thing on a wireless connection when there is packet loss freeze up the entire works. Wired is a little more friendly with packet loss then wireless.


It is an excellent post turtle and a very good question. More user inputs will be needed before we can conclude anything.

A good test would be the exact same setup on a non corperate firewall setting to see if it stills does it..


Please do not misunderstand me that I am not thinking you are having an issue that is not the case at all. I am just trying to help you isolate the cause of this problem so that a solution or workaround can be implemented..

[SuperTurtle]

wait maybe a miss communication here did all 3 attempts happen when you are on there corporate lan or did some of them happen when you are on your lan?? I have seen sonicwalls completey halt traffic on a vnc connection very quickly..

My system is complete separate. We talking about my home system, so I not on their corporate system. And as mentioned, my ISP been rock solid. So, when I speak of the corporate system, we talking about the end user that I am helping via SC. And, as mentioned, SC on their end is simply making a outgoing connection to my home system (in which the linksys box is forward ports to a repeater..and I connect to that repeater also.

I am in no way talking about that corporate network that looses it tc/ip connection, but only my end, and only my single desktop computer. And only while running the vnc viewer. I never run the vnc server on my end at all. I Only use the viewer, and SC on the other end.

In a sense, the above details are not really 100% important. What is important is that tc/ip services on that home computer stops when I loose the connection during the vnc session. Quite a amazing coincidence! (by the way, the repeater is running on another machine – not my computer I doing the remote support on).

As mentioned, the ONLY reason I got on to this idea was that I suspected that my ISP was killing incoming port 80 connections (makes sense, since a incoming port 80 would mean I running a web server on my home internet connection, which is a violation of the terms of agreement of my high-speed provider (Shaw cable).

So, I started to suspect that my ISP provider was shafting me. Thus, the instant I lost my VNC, I did a quick launch of browser, and a send/receive in my email ---- To my amazement, they both had stopped working. I instantly phoned my ISP..and I was fuming on the phone. They 100% assured me that they do not block, or re-set incoming port 80 connections.

Let me see if I am understanding you. Your server drop the connection to your home which you were accessing from a cooperate lan connection.. if there firewall quit sending the packets while your home pc was waiting form them it might cause a tcp/ip stack lock or crash. It should not but it is possible..

Well, actually, as mentioned, it not my server at all. Only the machine running VNC viewer that lost its connection, and that is my desktop computer.

More user inputs will be needed before we can conclude anything.

Yes, and it possible that my internet stack on my pc is damaged…who knows….

A good test would be the exact same setup on a non corperate firewall setting to see if it stills does it..

Sure, but as mentioned, they are just one of many people that I support. Last week I had another customer dropping the connection frequently, I just did not “test” if my local tc/ip services had stopped. In the future I will test this issue always. If the two events match all the time, then some type of buffer overrun, lost code pointers, or some memory management issue in the vnc code is casing the tp/ip stack to fail.

In fact in preparation for that demo tomorrow, I just noticed that ICS services are running on this computer, and they should not be (unless virtual pc uses that!!! – which I run and use a lot of ). In addition, while the wireless card is turned off, the Wireless Zero Point configuration service is also running.

So, for tomorrow, I tuning all of these off, and also turning OFF the windows firewall.

My hope (actually my hunch) is that my problem will go away!!!! I betting it one of the above that was casing this…

I be able to post back tomorrow as to how the demo went…..

Super Turtle

[SuperTurtle]

>able to post back tomorrow as to how the demo went…..

Well, it went flawless. I demoed for about one hour…..

So, while not a known perfect fix, I disabled windows firewall (xp), stopped the zero point wireless configuration service. I also disabled the ICS service (which apparently the firewall seems to need, or use).

Result….disconnects are completely gone…..

I will try some more support stuff today…but, it sure seemed to work for me….

Super Turtle.

[SuperTurtle]

>Result….disconnects are completely gone…..

Unfortunately, the disconnects have now returned....

So, disabling all that stuff did not help....

As mentioned, the “critical” symptom here is that all internet services stop on the computer. (other computers sharing the same router continue to function).

I had to re-boot the computer, and even then, the connection did not want to return….

After doing a “repair” connection, and re-booting…it came back….

This seems to hint at some type of buffer overrun, or something else that occurs when the error level is somewhat higher then normal. Once VNC viewer craps out….all internet services on my pc don’t work….

Super Turtle

[sbahour]

I'm a long time user and have recently been facting these session drops daily. I'm in the US (Ohio) and am connecting to a remote machine in the Middle East. It has been doing perfect for years and through many UVNC versions.

Today, I decided to spend serious time to find out what's going on. TO make a long story short, I ended up resetting TCP/IP stack on the remote machine via http://support.microsoft.com/kb/299357/

Now, I can't get a connection at all. Does UVNC need to be reinstalled on remote machine after this reset? I tried rebooting, which usually works when I have a session drop, but no luck.

Once I get back into the remote machine, I will look at the WinVNC.log as described above to learn more.

Thanks,
Sam

[YY]

What is the original TCP/IP configuration of that remote pc?

If that pc was using manual assigned fix IP, then the reset will erase such setting, and most likely the pc will under a new ip assigned from DHCP server (or the auto self assign ip if DHCP not available). Then the routing service may not be able forwarding the connection to this pc again.

Also if the IP is changed, the firewall may block the vnc session as the old rule is not applicable.

[sbahour]

You hit it on the head! Thanks.

Luckily, I had the remote mgt on for the modem/router and was able to see that the IP for the PC was changed. I'm in.

Now I can focus on why UVNC sessions are hanging with me. Very well could be the PC, albeit it worked fine for so long.

Tks again,
Sam

[sbahour]

Just a note on the issue of sessions freezing. Since I reset the TCP/IP stack on the remote machine via http://support.microsoft.com/kb/299357/ I have not had a single session freeze. This is after having 2-3 per day.

Rgds,
Sam