This post explains how to generate self signed certificates with SAN – Subject Alternative Names using openssl. It is a common but not very funny task, only a minute is needed when using this method.
The example below generates a certificate with two SubAltNames: mydomain.com and www.mydomain.com
Create openssl configuration file
Create configuration file for openssh (In a Linux … Read more
It is not the first time my Icinga suddenlty, stops showing the grafana graphs.
If trying to log to Grafana, admin password is not accepted. I am pretty sure i have not changed the password but I am unable to login to Grafana.
And even worse, given that I still have not configured Grafana SMTP section / admin … Read more
Here I am trying to present (I hope in an easy way to understand) some Icinga concepts (maybe also applicable in Nagios) like active and passive checks, enabling and disabling freshness checks, soft and hard states,… and the related parameters to configure them.
ACTIVE and PASSIVE services
There are two types of services:
- ACTIVE: Check initiated by the Icinga
… Read more
Exim is a very flexible and common MTA (mail transfer agent) in Unix systems.
This posts shows the way to configure Exim as client to send authenticated and encrypted (TLS) emails through a smarthost.
Lets suppose the smarthost email server is listening on port 587 for secure outgoing SMTP…
Configure exim to use the smarthost
To configure exim In … Read more
To configure passive checks in Nagios/icinga I use a tcp listener daemon that launches a script (See Nagios – Using passive checks without agent)
Tried to use inetd superserver daemon, but in the last versions, i have not been able to make it work correctly (See last update in my post: Linux – cannot found / missing inetd.conf)… Read more
Trying to configure a new inetd service needed for my Icinga (see Linux – Create custom inetd service), but i have not been able to find the inetd.conf file.
It seems inetd is not installed by default in the last Debian versions (mine is 9 – stretch).
Luckily, it is packetized in the inetutils-inetd
# apt-get install inetutils-inetd
… Read more
This post shows the steps to create a multiboot cd with multiple Linux distributions or tools.
For example, I created a recovery / disaster case cd with the following tools:
– Clonezilla (to clone/recover disks and partitions)
– Gparted (partition editior with GUI)
– Trinity Rescue Kit (linux distribution for recovery and repair operations on Windows machines)
The Multicd … Read more
If you need to update automatically a DNS entry with your public IP address (for example, to allow remote access to your home Raspberry or Linux), you can use the no-ip provider and its Linux or Raspberry client.
This posts shows the way to install the client and how to configure it to be started at boot time.
… Read more
For certain application, a job partner asked me to send him certain certificate with private key in PEM format. Normally I’m using PFX format, but with a little help of the openssl toolkit converting PFX to PEM is quite easy.
openssl for windows can be downloaded here: http://gnuwin32.sourceforge.net/packages/openssl.htm
After extracting the contents, inside the bin subfolder the openssl … Read more
Maybe you have tried to execute the top command to monitor processes on a remote host.
Error remotely – Run it in batch mode
If so, the following error can be returned:
$ ssh user@remotehost top -n1
TERM environment variable not set.
top does not work remotely in the default “interactive” mode. Use the “-b” parameter to run it in … Read more