Recent Posts

How to configure the firewall using firewall-cmd ?

In the last article, we have opened the port (80) for http service using firewall-config graphical utility in Redhat Enterprise Linux  7.  As a Unix/Linux admin , would you prefer to use “GUI” over “command line” ? I don’t think so. Most of the Unix/Linux system administrators will go with the command line. firewall-cmd is a command line utility which interact …

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Playing with firewalld on RHEL 7

The Linux kernel includes a powerful network filtering subsystem called netfilter.  The netfilter subsystem allows kernel modules to inspect every packet which are travelling to the system. Any incoming, outgoing and forwarded network packets cab e be inspected, modified ,dropped or rejected in a programmatic way ,before reaching to the user space. But these programs needs to be defined and …

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Are you in VM or Physical host ? RHEL -7

The whole world is moving towards virtualization. Unless you maintain the inventory on CMDB , it is very difficult to find the server location and configuration. The hyper-visors like VMware vSphere, Microsoft Hyper-V,  Xen and KVM supports Linux as virtual machine. If you have the proper CMDB for the virtual machine, you can easily find the hyper-visor for the VM …

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Disk Partitioning – MBR vs GPT on RHEL -7

Disk partitioning allows a hard-drive to be divided in to multiple logical partitions on Redhat Enterprise Linux.  The multiple partitions can be used to create filesystems and it can be mounted in different mount points. Most of the operating systems are still using the MBR partitioning scheme and it has dictated how disks should be partitioned on systems running BIOS firmware. …

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RHEL – 7 Network Management – nmcli or nmtui

nmlci is a wonderful command to configure the network profiles on Redhat Enterprise Linux 7.  nmcli also supports the command completion function by pressing “tab” key but still you need to use the quotes properly.  nmtui is an alternative command for nmcli which is based on “Text User Interface”.  It will be useful for RHEL-7 Beginners but experienced system administrators …

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RHEL – 7 Managing the network with Network Manager

In the last article, we have seen that how to review the current network configuration in RHEL 7. Redhat has introduced the profile based network management on Redhat Enterprise Linux 7. Network manager is a daemon that monitors and manages the network settings. Network manager can be managed using nmcli and other graphical tools. These tools will automatically update /etc/sysconfig/network-scripts  in the …

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RHEL 7 – Networking overview

Redhat has made a lot of changes in the RHEL-7’s networking part. In Red Hat Enterprise Linux 7, the default networking service is provided by NetworkManager, which is a dynamic network control and configuration daemon that attempts to keep network devices and connections up and active when they are available. The traditional ifcfg type configuration files are still supported.  To view the current network …

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Redhat Enterprise Linux 7 – systemd targets

Redhat Enterprise Linux 7 ‘s booting process also modified lot when you compare to the earlier versions. Instead of grub ,we have grub2 in RHEL 7  to boot the system. The boot loader loads the configured kernel and initramfs from disk to memory. An initramfs  is a gzip-ed cpio archive containing kernel modules for all hardware which required at boot, init …

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Service Management (systemd) – RHEL 7

Prior to Redhat Enterprise Linux 7 operating system, init was the process which is responsible for activating the other services in the system. There were daemons and many system V LSB scripts were started at the boot time. These are mostly likely the shell scripts which resides under the /etc/init.d directory and called on the different run levels. But this system has lot of …

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