Archive for category Server

How to check the expiration date of a ssl certificate?

To check a certificate of an host:

openssl s_client -servername your.domain -connect your.domain:443 2>&- | openssl x509 -enddate -noout | sed 's/^notAfter=//g'

To check a certificate file:

openssl x509 -noout -enddate -in your.crt | sed 's/^notAfter=//g'



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Apache failed on system boot, when binding to an additional IP

Starting point:

My system (Ubuntu 18.04.1) is a VPS running on KVM. The network with some additional IPs is configured with Netplan.



The Apache server is running on an additional IP. If the VPS reboots, the apache didn’t start because, it couldn’t be bind on an aditional IP. A log entry like the following can be found:
apachectl[631]: (99)Cannot assign requested address: AH00072: make_sock: could not bind to address [xxxxxxxx]:80

But if you restart Apache after the reboot, it runs as expected!
Strange, isn’t it?



Ok, I couldn’t find the exact reason of this reason. But I think, there is a strange timing issue on reboot. The network isn’t completely up before Apache is starting.

To solve the problem, just edited the section ‘Unit’ in the file /lib/systemd/system/apache2.service and replace


That’s it!

More information about the network-target can be found her:

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VPS boot overrides some configuration files

Problem: I bought a new VPS and did some configuration changes (e.g. hostname setting). I’ve installed some software and wanted to test if my settings are boot resistant. And every time the VPS was¬† booting the files /etc/hosts and /etc/hostname was overridden by the defaults of the provider.

Reason: Virtuozzo (the software which virtualises my VPS) overrides those files at every  time the VPS is booting.

Solution: Replacing the files /etc/hosts and /etc/hostname at boot-time.

The following description is applied for Ubuntu 14.04. Both replacements are implemented as upstart jobs.


Copy the /etc/hosts (e.g. /etc/hosts_my) and adapt it to your needs. Then create the file /etc/init/hosts.conf with the following content:

description "restore my hosts"
start on startup
exec cp /etc/hosts_my /etc/hosts


Copy the /etc/hostname (e.g. /etc/hostname_mod) and adapt it to your needs. Then edit the file /etc/init/hostname.conf and change the last exec command to:
exec hostname -b -F /etc/hostname_mod

That’s it!

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