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Sometimes on Oracle Linux there is problem, when you try use “yum” and get error like this: The fixing of this problem, you can try rebuild db: And then should work: That’s all!

The best way to check information about domain and DNS configuration is “whois” and “dig”. This tools can provide a lot of informations. Lets try use it. First we must check that package is installed.I have already installed “dig”: In debian, you can use “dpkg -S” if you don’t have it then you should install: […]

Sometimes it is necessary to change the DNS name indication to a different IP address. As you can see in the example below, google.com currently points to: To change google.com indication to, for example – 37.187.101.239, edit the file: “/etc/resolv.conf” as root: After making this change, the effect is as follows: Windows as you see […]

A convenient way to maintain the test environment is automatic updating.However, remember to set the backup, e.g. the day before – I always set it like that in proxmoxe.The script that updates the Debian system looks like this: You can download the script from: The script cleans unnecessary deb files after the update.Keep in mind […]

This script send you e-mail notification about new updates: You can download the script from: You should set the correct e-mail address in the script, for now it is soban@soban.plNotification it’s looks something like that: Should the script be executed: Also added to the crontab, every day to extend a new update: Remember don’t to […]

Reviewed on 28 October 2026. This article originally described upgrading Debian 10 (buster) to Debian 11 (bullseye). It has been rewritten because the old commands are unsuitable as a current production runbook. Debian 11 LTS ended on 31 August 2026. Reaching Debian 11 is therefore no longer a sufficient migration goal. Choose a supported destination […]

Nmap – scanning SSL/TLS ciphers on Debian 11 In this example we are working on Debian 11 (Bullseye). First, let’s confirm the system version: Nmap is one of the most powerful network scanning tools available on Linux. It allows you to scan open ports, detect running services, identify software versions and analyze supported SSL/TLS protocols […]

SSLScan is a command-line tool used for SSL/TLS vulnerability scanning. It is used to detect SSL/TLS vulnerabilities and weaknesses on servers that use SSL/TLS. SSLScan supports all SSL and TLS protocols and cipher suites, including new ones such as TLS 1.3. SSLScan can be used to identify various SSL/TLS vulnerabilities, such as weak ciphers and […]

Script to help check if the domain is expiring (don’t forget change e-mail in script – now is soban@soban.pl): This way you can download the script and give it permission to run: And now we can add it to crontab, on monday for example: