Debian

Introduction Some time ago I tried to configure a SMTP server in a host in the cloud, but because of some restrictions, the emails from that server were bounced. The problem was that the hosting provider didn’t configure the PTR DNS entries (more about DNS PTR entries) for some kind of hostings. When this happens the best solution is to use a SMTP relay server, by this way that server is in charge of the final delivery of the emails. There are some services such us Sendinblue which offers 300 mails per day in the free plan. I believe it’s enough for a normal use of a mail server. ...

First off, as a prerequisite it is needed to have a CLI access to the Debian OS. It can be done using a keyboard and a screen connected to the Raspberry Pi, or using a SSH connection. If you have followed the post of how to install Debian On a Raspberry Pi 4, you should be able to access with SSH using the Ethernet (RJ45) port. Also, you should have the SSID and the password of your Wi-Fi connection, and it should be enabled the DHCP protocol in your router. ...

I have several Raspberry Pi and in all of them I have used the Ubuntu distro. However I also wanted to use Debian as it is one of the most used Linux distros. Besides Ubuntu is based on Debian, so I guess I will feel confortable with it. Debian vs Ubuntu Debian is more stable than Ubuntu, indeed, it is one of the most stable Linux. The releases in Debian are not as frequent as in Ubuntu, and the software updates in Debian usually don’t have the latest versions. Besides, Debian is lighter because the software it has is the basic one. ...

This blog have several items related to Raspberry. I decided to created this page to have all Raspberry Pi related posts, ordered. Info How to know which Raspberry do you have How to install Ubuntu in your Raspberry Pi 4 without Keyboard nor screen How to install Debian on a Raspberry Pi How to change the hostname in Ubuntu How to change language and timezone in Ubuntu Customization Customize the terminal with screenFetch How to add alias to your Linux Customize bash prompt with colours in Ubuntu Networking How to set up Wi-Fi on Ubuntu running on the Raspberry Pi 4 How to set up Wi-Fi on Debian running on the Raspberry Pi 4 How to resolve LAN hostnames with Ubuntu Monitoring How to Monitor an Ubuntu Server with Grafana and Prometheus How to monitor network traffic with vnStat Mail Configure Postfix to send e-mail using Sendinblue as SMTP server Security Protect your server with Fail2ban Integrate AbuseIPDB with Fail2ban Users How to create a new user in Ubuntu from terminal How to activate SUDO for a user in Ubuntu

In some situations we need to know which packages we have installed in a Debian or Ubuntu system. In that case, we can use the tool dpkg, which will give us the information we need. dpkg Next command will give us the current packages installed with different states: dpkg --get-selections The states we can have are: install: The package is selected for installation. hold: A package marked to be on hold is not handled by dpkg, unless forced to do that with option –force-hold. deinstall: The package is selected for deinstallation (i.e. we want to remove all files, except configuration files). purge: The package is selected to be purged (i.e. we want to remove everything from system directories, even configuration files). If we want to filter packages, we can combine dpkg tool with grep tool. Here an example to filter the packages related with nginx: ...