CentOS/RHEL 7

Question: How do I stop the xinetd daemon from starting VNC Server processes? 1. Go to xinetd configuration file /etc/xinetd.d/vnc-server. Modify the file and look for the line disable = no and set the value to yes. # vi /etc/xinetd.d/vnc-server service vnc-server-1 { disable = no socket_type = stream protocol = tcp wait = yes […]

The GNU Network Object Model Environment, also known as GNOME, is a powerful and easy-to-use environment consisting primarily of a panel, a desktop, and a set of desktop tools with which program interfaces can be constructed. GNOME is designed to provide a flexible platform for the development of powerful applications. But sometimes, you may want […]

The route command is used to show/manipulate the IP routing table. The simplest command with ‘route’ is to run it without any options or arguments which will return the IP routing table. The equivalent command with ip is as follows: $ ip r where r stands for route. The route command was deprecated in CentOS […]

The Problem When running the systool command on CentOS/RHEL 7, the following error message is reported: # systool -c fc_host -v Error opening class fc_host The Solution The error occurs because the scsi_transport_fc module that is responsible for populating the contents of /sys/class/fc_host/ directory is not loaded on the system. 1. Manually load the scsi_transport_fc […]

The Problem Attempting to start the NFS (nfs-server.service) on CentOS/RHEL 7 fails as follows: # systemctl status nfs-server.service nfs-server.service – NFS server and services Loaded: loaded (/usr/lib/systemd/system/nfs-server.service; enabled; vendor preset: disabled) Drop-In: /run/systemd/generator/nfs-server.service.d ‘-order-with-mounts.conf Active: inactive (dead) Mar 09 16:17:10 hostname systemd[1]: Dependency failed for NFS server and services. Mar 09 16:17:10 hostname systemd[1]: nfs-server.service: […]

If you want to change Port in the Apache configuration file it’s easy to do. You can also run a website on a different port rather than the default port. 1. Let’s check which is listening to which service: # nmap -sT -O localhost 2. Check whether Port 8000 is free or not: # lsof […]

The Problem Running the ‘dnf update’ command fails with below error: # dnf update Error: Problem 1: package perl-4:5.26.3-419.el8.x86_64 requires perl-interpreter(x86-64) = 4:5.26.3-419.el8, but none of the providers can be installed – cannot install both perl-interpreter-4:5.26.3-419.el8_4.1.x86_64 and perl-interpreter-4:5.26.3-419.el8.x86_64 – cannot install the best update candidate for package perl-interpreter-4:5.26.3-419.el8.x86_64 – cannot install the best update candidate […]

This post describes an approach to configuring sssd in order to interact with multiple Active Directory Domains located in different forests. This method involves altering /etc/krb5.conf and /etc/sssd/sssd.conf files. 1. Join the first domain (domain1.com) from the first forest. # realm join –verbose domain1.com -U LinuxAD@DOMAIN1.COM 2. Edit /etc/krb5.conf file and add the secondary domain […]

The Problem On CentOS/RHEL, the OpenSSH SSH Daemon (sshd) utilizes port 22 for incoming connection requests from remote OpenSSH SSH (ssh) and Secure File Transfer (sftp) clients. In some cases, however, System Administrators prefer to utilize separate ports to service ssh and sftp activity. In One such case, system administrator is facing below error while […]

This post describes the PAM pam_cracklib credit system in relation to Linux PAM password complexity. Overview of PAM The Pluggable Authentication Modules (PAM) is a central, flexible, modular framework used to manage system authentication policies and facilitate user authentication. PAM provides a general Application Programming Interface (API) that privilege granting programs defer to for user […]