Strange OS X hangs

[bkocik]

For more than a week now, I've been experiencing strange crashes/freezes with OS X. The following always happen, and always in this order:

1) I notice that I can no longer resolve hostnames, but existing network connections (to databases, and ssh, etc.) still work
2) Shortly thereafter, I discover I can't launch any new applications - they bounce in the dock, and never appear on screen
3) Next, Finder and the dock become extremely sluggish, or unresponsive altogether, and things start beachballing all over the place. I also cannot quit any applications (the dock won't bring up contextual menus, I can't launch the "Force Quit" dialog, and QuickSilver fails to kill anything I ask it to)
4) Having no other choice, I power off and power back on.

I've been trying to find the cause of this for a week, and the one thing that appears to be the common thread is this: I have recently connected to a VPN with Viscosity. I don't know for sure that it is Viscosity's doing, and it may well not be; I'm posting here to see if anyone else has had a similar experience.

Setup: Leopard (10.5.5) on a MacBook Pro, 2.4Ghz Core 2 Duo, 4GB RAM, Viscosity 1.0 (licensed).

-Bill

[bkocik]

A little more information: It's definitely the act of connecting to a VPN that's initiating this crash sequence. However, the exact same thing happens if I use Tunnelblick to connect, so it's definitely not Viscosity's fault.

My guess: It's something to do with the VPN client swapping my DNS settings and/or routes that is choking OS X. If anyone has ideas of how to further isolate the problem, I'd be grateful to hear them.

-Bill

[James]

My guess: It's something to do with the VPN client swapping my DNS settings and/or routes that is choking OS X.

Well you could check this by turning off Viscosity's DNS support (untick "Enable DNS/Nameserver support" under the General tab).

You could also try uninstalling and reinstalling the tun/tap drivers (the most likely candidate). Viscosity will install and use the latest tun/tap drivers if necessary, however as you have used Tunnelblick in the past it is possible you might be using older an older version of the tun/tap drivers. Try completely uninstalling the drivers, and then restart your computer and try connecting again with Viscosity. You can uninstall the drivers by removing the following:
/Library/Extensions/tun.kext
/Library/Extensions/tap.kext
/Library/StartupItems/tun
/Library/StartupItems/tap

It would also be worth checking the OpenVPN log in the details window - are there any error messages?

Cheers
James

[Paleck]

I can corroborate what bkocik is saying. I just installed Viscosity and since then I have completely locked up my machine (and had to power it off) 6 times in the last hour. I have never had any other vpn software installed on my computer other than the default PPTP and L2TP that comes standard with OSX. One guaranteed way to lock up the machine is to do something very processor intensive. IE iTunes, a movie or for a nearly instantaneous lock-up World of Warcraft.

[paleck]

I forgot to mention that even with Viscosity not even running (so only whatever boot time drivers are loaded) it will still lock-up.

[James]

I forgot to mention that even with Viscosity not even running (so only whatever boot time drivers are loaded) it will still lock-up.

If Viscosity is not even running the only thing active would be the tun/tap drivers, which are installed when Viscosity is first launched.

Have you tried uninstalling the drivers as mentioned above?

You can also try installing the tun/tap drivers directly from:
http://tuntaposx.sourceforge.net/download.xhtml

Cheers
James

[Philipp Schmid]

Hi,

we have the same problem on multiple machines, this makes viscosity unusable!

Lg Philipp

[paleck]

As it turns out it was just bad timing. I got hit with that wonderful problem with nvidia chips in semi-recent macbook pros. I attributed my problems with my laptop to viscosity because my problems started two hours after i installed it. Sorry about that. It's working great now!

More information on the Nvidia 8600 Chips and Macbook Pros:
http://support.apple.com/kb/TS2377

[James]

we have the same problem on multiple machines, this makes viscosity unusable!

If the freezes occur while Viscosity isn't even running I'd recommend re-installing the TUN/TAP drivers as described above. paleck also raises an important point: it's also worth checking for other unrelated software and hardware issues on the machines that could be causing the problem.

As for hangs only while Viscosity has an active connection, I'd recommend trying the latest build of Viscosity. Some applications, including Mac OS X, can hang if your DNS servers drop out or become un-contactable. The latest build of Viscosity addresses a situation where this might occur. You can download the latest build at:
viewtopic.php?f=7&t=34

Finally, there is a known issue with OpenVPN on Mac/BSD Operating Systems for UDP connections. In certain situations your OpenVPN log may start filling up with "No buffer space available" error messages. These may come rapidly enough to cause the openvpn process and Viscosity to hit 100% processor utilisation. It's a fairly rare occurrence, and something we're hoping to have Viscosity address in a future version. It's worth checking the OpenVPN log in the Details window to see if this may be the case. You can also find a great deal of discussion about this on the OpenVPN mailing list.

Cheers
James

[randykahle]

I have noticed these hangs also.

I tried everything I could think of to isolate them - testing/changing RAM, reinstalling OS X and using SuperDuper's Sandbox to be able to rollback updates, etc., etc.

My symptoms also include a blank blue screen when I try to do a user switch while connected on the VPN.

I will continue to monitor my freezes and report back anything I can figure out.

-- Randy