commands - cloud-admin.pl

2024-02-072024-02-08 kazmen Uncategorized

How about env variables

I was wondering about env variables in Linux system. Many users using them to setup applications. But did you know about env variables are visible to other ?

Long time ago, there was one system per server and everything was correct. But now systems, especially in cloud environments are used by many users.

Let’s see what exist in file /proc/1/environ

As you can see there is some system variables set in those file.

But many sites are using env variables to pass application specyfic setting like users and passwords… Now you know.

2022-09-272022-09-27 kazmen Uncategorized

How to encrypt data using openssl

openssl enc -e -aes256 -k '<passphrase>' -in <decrypted_file.txt> -out <encrypted_file.txt>

2022-09-272022-09-27 kazmen Uncategorized

How to wipe disk using linux on a pendrive?

-> https://www.debian.org/CD/faq/#write-usb

After a booting Debian from usb please check what You have on Your computer:

blkid

Next you can use linux to wipe data from hard disk:

dd if=/dev/urandom of=/dev/sdX bs=1M; sync
where X is drive in linux system ie /dev/sda

2022-09-272022-09-27 kazmen Uncategorized

How to upgrade from Debian 10 to Debian 11

Whats new in Debian 11?

-> https://www.debian.org/releases/bullseye/amd64/release-notes/ch-whats-new.en.html

For the security reasons please backup before procedding with upgrade.

Make sure You have upgraded your debian distribution to the latest old-stable release. Run following commands from the console:

sudo apt-get update
sudo apt-get upgrade

If you are up-to-date with Debian 10 distribution you can proced to the next chapter:

Upgrade to Debian 11:

First edit with your favorite editor the /etc/apt/sources.list file. You can change the file also with sed command:

sed -i 's/buster\/updates/bullseye-security/g;s/buster/bullseye/g' /etc/apt/sources.list

After that you are able to upgrade to the Debian 11 system by running following commands:

apt-get update
apt-get upgrade
apt-get dist-upgrade

Next we must reboot into new system 🙂

2022-09-272022-09-27 kazmen Uncategorized

Few Linux commands

Linux system offers in command line mode a full set of commands for users and also for administrators.

I will present some of this in this post.

man command_name

Where command name is any Linux command we are interested in using.

The man command displays a manual that lists the syntax and an overview of all the options for the command given as an argument. In the case of administration commands or system services, it also gives any file names that contain definitions of the default behavior of these commands.

The work with the manual is finished after pressing the q key.

example:

man cd

cd command is used for changing the current directory.

The paths in a Linux system can be specified in relative or absolute terms.

example:

cd ../

In a bash shell, you can use the tab key to complete a directory name.

2021-02-122022-09-27 kazmen Uncategorized

How to audit user commands in Linux Debian

I was wondering how to audit user or root commands in bash/sh and founded that simple script written in bash is very basic. For example when type sh command the looging in bash stopped working.

I founded the simply and very good application called snoopy

To install snoopy in Debian Linux type following command:

sudo apt-get install snoopy

Of course chose yes

Tak in Polish means yes, Nie in Polish means no.

Now logout and login back to server the logs of command line should be in the following location:

sudo tail -f /var/log/auth.log