The Geek Diary

CentOS/RHEL

Xen Hypervisor (xm) command Cheat Sheet

by

Generally, you will use virsh to control VMs, but there are a few useful functions you can get from xm but not virsh. We cover the most common commands here. How to list the currently running VM on physical server? # xm list Name ID Mem VCPUs State Time(s) 0004fb00000600004689b1d1cc6e83d9 1 1027 1 r—– 293.5 […]

IBM DB2 Installation on Red Hat Enterprise Linux

by

IBM DB2 database can be installed on Linux, UNIX, or Windows operating systems. We are going to install DB2 Version 10.1 on Red Hat Enterprise Linux Server from the command interface. IBM DB2 is a next-generation data platform for transactional and analytical operations. Step 1: Download IBM DB2 Package for Red Hat Linux from following […]

Configure VSFTPD Chroot Environment in CentOS and RHEL

by

vsftpd stands for ‘Very Secure FTP Daemon’, is an FTP server for Unix-like systems, including Linux. When we configure vsftpd, all FTP users can move to other’s directories from their home folders. In this article we will make the changes in the vsftpd server so that user’s are limited to their home directory only. This […]

pam_tally2 command – lock & unlock ssh failed logins in linux

by

pam_tally2 command is used to lock and unlock ssh failed logins in a Linux-like operating system. To implement a security feature like a user’s account must be locked after a number of failed login attempts. We can achieve this security via pam module called pam_tally2. This module can display user’s login attempts, set counts on […]

Detect and Scan New Luns in CentOS/RHEL

by

While Working on the Linux boxes, sometimes the Linux admin has to scan new storage or LUNs assign to the server from the Storage team. In Redhat Linux and CentOS we can scan the LUNs either using the script ‘rescan-scsi-bus.sh’ or using the ‘/sys/class’ files without rebooting the server. In my scenario, I have 4 […]

KVM Virsh Command Examples on CentOS and RHEL

by

virsh is the interface or command for managing the virtual machines based on the KVM hypervisor. On virsh interface virtual machines are identified by their domain names, so virsh is generally used to list current domains, to create, pause & shutdown domains. Virsh comes under GNU Lesser General Public License and supports Xen, QEmu, KVM, […]

Glusterfs – Advanced Troubleshooting Tips and Tricks

by

Friends continuing with the advanced know-how and troubleshooting on glusterfs.In this article, we have a 3 node cluster running on glusterfs3.4. Below are the steps that are used for glusterfs troubleshooting. Step 1: Check the Gluster volume status and information. [root@gluster1 ~]# gluster volume info Step 2: To verify all the details of the replication […]

Integrate Linux Servers with Active Directory using Samba, Winbind, and Kerberos

by

In this tutorial, we will discuss how to integrate Linux Servers(Centos/RHEL) with Windows Active Directory for authentication purposes. In my case, I have Centos/RHEL 6 servers. Follow the below steps to integrate these servers with AD using samba, winbind, and Kerberos. Step 1: Install the samba-winbind and kerberos packages. # yum install samba-winbind samba-winbind-clients samba […]

Zenoss Core Installation & Configuration on CentOS/RHEL 6.X

by

Zenoss is an open-source real-time monitoring tool and comes under GNU General Public License (GPL) version 2. It provides a web interface that allows system administrators to monitor availability, inventory/configuration, performance, and other events. Most Common Features: Application, Network and Systems Monitoring and Management Alerting and Automatic Remediation System Log Monitoring and Event Management Automated […]