Somewhere there is a physical network card – checking the firewall/router for traffic is a good idea no matter what it is running on. VMs have lots of clever software to isolate each instance (including resources) and you may be being streamed at a rate the VM as whole can handle, and your isolated VM cannot. And setting the debug level up is still a good idea. And forcing core files and using a debugger is still a good idea. And trying inetd mode is still a good idea. You need to narrow your focus and each of these suggestions will tell you something that narrows the problem. Eric

From: Murrey, Brian J. [mailto:Brian.Murrey@trimedx.com]
Sent: Thursday, October 18, 2018 7:14 AM
To: Eric Eberhard <flash@vicsmba.com>; stunnel-users@stunnel.org
Subject: RE: [stunnel-users] CPU 100%

Thank you Eric, this server is a VM running under vSphere 6.5 and has no physical network card.

From: Eric Eberhard <flash@vicsmba.com>
Sent: Wednesday, October 17, 2018 7:56 PM
To: Murrey, Brian J. <Brian.Murrey@trimedx.com>; stunnel-users@stunnel.org
Subject: RE: [stunnel-users] CPU 100%

Long ago I had a server with a bad network card. Every once in a while it would spew uncontrollable bytes onto the network. If you open a stunnel connection and it does that this could very well be the problem. If it cheap, try changing the network card. If not, you should be able to look in your firewall/router and it will tell you who is sending what bytes to whomever. See if that machine is indeed streaming the bytes in massive quantities. If not, I would suspect your stunnel is getting stuck in it’s own loop. There are a million reasons this can happen (well a few less than a million) – such as maybe a bad library in the FreeBSD or a bad choice in the Makefile – such as doing threads or something in a way your O/S does not like (I use threads=fork or whatever it is, instead of actual threading). You might tinker with some of the options that make the stunnel build and try different ones. Especially if stunnel was compiled on a different version of the O/S – could be differences in bytes in things and who knows what.

That is all I can suggest beyond setting the debug level to 7 (I think is highest) and then watching the log file.

Eric

From: stunnel-users [mailto:stunnel-users-bounces@stunnel.org] On Behalf Of Murrey, Brian J.
Sent: Wednesday, October 17, 2018 10:57 AM
To: stunnel-users@stunnel.org
Subject: [stunnel-users] CPU 100%

We are running stunnel 5.49 on FreeBSD 11.2 and we’re running into a problem once in a while.

CPU pegs at 100% when we get an stunnel connection from one of our external devices.

This affects 100% of all cores and we can’t even log in to console.

To mitigate this temporarily, we have a script running in the background to watch when stunnel begins to spike and restarts the daemon.

It doesn’t happen 100% of the time, and so far I have been unable to distinguish what makes the connection do this to the CPU.

Have any of you run in to this issue?

Sincerely,

Brian Murrey
System Engineer II, IT Infrastructure

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