Tag archive: linux

Thanks to this lab with simple topology we will study, how to configure iSCSI protocol in Linux and SAN environment. We gonna pass through iSCSI, Network File System and Server Message Block (SMB) also known as CIFS and at the end of the day we will be able to use  resources in SAN connected to…

Logical volume manager is a storage virtualization that allows us easily manage the disk space. Without any problems we can expand, shrink, add disks to the virtual Volume and for the sake of redundancy apply RAID if required.

Linux provides 3 levels regarding filesystem security: standard permissions, ACL and SELinux. SELinux handles not only with files permissions but with applications, resources and network ports as well. SELinux may put a ban on an application access to the spicified system files or may not allowed a user changing file permission. What is, how work and how to…

Firewalld alike iptables relies on Netfilter service that is responsible for packets filtering.The difference is that iptables works based on “chain of filter” rules, alike ACLs on the router, firewalld based on “zones” similar to ASA. The idea that stands behind the firewalld is that interfaces and networks are grouped into zones. Each zone has different…

GRUB – GRand Unified Bootloader plays crucial role in proper and stable work of a Linux system. Thanks to its the Linux is able to load  the system in different modes but also enables us to recover the OS if something went wrong or the system got crashed.

Dealing with freshly added hard drives to the system is not difficult, but as every system manipulation in Linux requires a CLI knowledge. This article allows you adding seamlessly hard drive to the system, partitioning and mounting its permanently thanks to fstab file.

Rsyslog and journald daemons gives you an opportunity to control what happens in the system. You may trace users and their interaction with other daemons. They increase  security, cause based on the logs you can make decisions regarding users that unusuall  behaviour you’ve noticed. Also, if there is a problem with system stability or system is not running…

Even very well designed operating system as Red Hat without software is worth not too much. In Red Hat and CentOS we use the same tools to get the programs and keep them up to date. Let’s have a look on RPM and YUM package manager.

If we run any file server or backup server that require high availability and redundancy the first thing that we should think about is RAID array, especially in Linux environment, where creating and configuration is easy to make. Let’s configure simple RAID 1 mirroring with 2 hard disks from a scratch.

In linux environment if you are going to move between graphical and text modes, knowing runlevels or boot targets is fundamental. Also is important how to manipulate and modify particular targets and services that are being run with them.

In the course of time the CLI tools that have appeared in particular versions of Linux distributions evolved significiantly. From ifconfig through ip to the nmcli and many other like ss, isof etc. Let’s have a look at Linux from  the perspective of networking, its configuration, management and troubleshooting.

Crone and NTP (network time protocol) services are to some extent linked with each other despite they do completely different things. Crone is responsible for automating of processes, NTP for keeping time on our server up to date, but correct work of Crone is dependant on correct work of NTP.

PID stands for “process ID” that have got every process in the system and thanks to this can be easily identified. This identification is necessary when we are going to send “signals” to a given process.

Traditional access permissions for files and folders  in Linux distributions enables us control of granting access to files/folders and what users can do with them. Not complicated, easy to understand and crucial to working with a file system. 

After the GRUB finds the kernel, continues the boot process with the first and most important,  systemd process.  Systemd takes part nearly in every activity in Linux and nothing happend without its knowledge.