Linux

OpenVPN in Ubuntu 18.04 Foo within OpenVZ Container (Strato)

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It has been a while since my last blog post, but there was no real foo happening to me during that time. But this issue really gave me some heartburn.

Let’s start with the general setup. We have a Linux VM in an OpenVZ environment. The hoster is Strato in Germany, but I don’t think that really matters. There are some known issues with the TUN device not being accessible within the VM, but Strato did their homework and I could see the module:

# lsmod | grep tun
tun                     4242  -2
vznetstat               4242  -2 tun,ip_vznetstat,ip6_vznetstat
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OpenVPN 2.4 CRL Expired Foo

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I chose a nice Friday evening and a good Scotch to upgrade an older Ubuntu LTS to the latest and greatest. And all went well, until I wanted to connect one of the clients via VPN. All I saw was this nasty little line in the log files of the server

... VERIFY ERROR: depth=0, error=CRL has expired: ...

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Send Email from the Command Line using an External SMTP Server

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Sending email in Linux is pretty straight forward, once an email server is set up. Just use mutt or mail and all is good. But sometimes you actually want to test if SMTP is working correctly. And not only on your box, but on a remote box. That is of course easy using a MUA like Thunderbird or Sylpheed, but that is not always feasible on a remote server in a remote network.

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Check SSL Connection Foo

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It was that time of the year, when I had to renew some SSL certificates. Renewing and updating them in the server is a nice and easy process. But checking, whether the server is delivering the correct certificate and, that I updated and popluated the intermediate certificates correctly, is a different story.

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Nagios Enabling External Command on Debian based Distributions

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While debugging my check disk problem after the 15.10 upgrade, I saw that I forgot to enable external commands. That is handy, when you want to re-schedule a check to see, if your changes took effect. Again, something that is easily activated. So if you see something like this, then you might want to make some changes:


Error: Could not stat() command file ‘/var/lib/nagios3/rw/nagios.cmd’!


The external command file may be missing, Nagios may not be running, and/or Nagios may not be checking external commands. An error occurred while attempting to commit your command for processing.
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