Manage System Logs with Graylog and rsyslogd

Graylog is widely used for log management and analysis. There are 4 main components of Graylog: Graylog Server MongoDB ElasticSearch NGINX as ReverseProxy to secure Graylog API Below steps will help, reader to basic installation of Single Node Graylog server and redirect system logs from rsyslogd to Graylog. Do let me know your queries on ngurjar…

HowTo: Add CentOS7 machine to Windows AD

Microsoft Active Directory(AD) is widely used in Enterprise for Centralized Authentication, Pushing Security related Policies, etc. Administrator may need to add CentOS7 machines to AD to use same user credentials. This blog will provide steps to add CentOS7 Linux machine to AD. There are multiple ways to achieve this and it is one of the way.…

Linux: Troubleshooting Filesystem Full issue due to open files

We face filesystem Full issue in our day to day Linux Administration. This issue is mainly related with /var, /home filesystems. If both are in / filesystem then it will impact / filesystem as well. When we face this type of issue, our first solution is to delete or truncate log files, temp files, hidden…

Exim Mailqueue Monitoring Script

This script will count number of mails in queue and validate with threshold value. If it is more than it will send an email using thirdparty tool called SendEmail. One important point to note, that is we need to use SMTP hosted on other server. Thats why we are using SendEmail perl script. We need…

Steps to Install and Configure VerticaDB on Cloud

  Steps to Install and Configure VerticaDB on CentOS 6.x on Cloud: Vertica require Swap space. So if you dont have Swap on your cloud, you can still create by using below steps: It also require transparent_hugepage to be disabled and tuning of few more system parameters. It is better to add them in /etc/rc.local…

Bare Metal Provisioning of Linux (Proxmox) using FAI

By Neelesh Gurjar What is Remote unattended installation? Remote unattended installation means installation of remote server without any human interference. This process is very useful for bare metal provisioning, automated installation on multiple servers, etc. What is Proxmox? Proxmox is debian based OS, which provides Virtualization Platform like VMware. https://www.proxmox.com/en/ What is FAI? FAI is…

Setting up Self Healing Tomcat

System Administrator has to configure Critical services regularly. He/She also needs to monitor that services and if services stop then needs to start them. We can automate starting of service after failure using Daemontools/supervise. We can also use monit for same. In this note we will configure Daemontools to monitor Tomcat service and if Tomcat crashes, Daemontools…

Configuring lbaas in OpenStack

My scenario: Openstack enviornment is configured on 3 nodes with CentOS 7 & OpenStack Juno. srv1 -> Controller node, Compute, Neutron Server, Cinder srv2-> Compute Node srv3-> Neutron Network Node, Compute Node Virtual Architecture of Load Balancer as a Service (lbaas) : Steps: 1. Install haproxy on all nodes as it is used as loadbalancer…

Change name of Network Interface in CentOS7

1. Open /etc/default/grub vi /etc/default/grub 2. Add net.ifnames=0 biosdevname=0 to GRUB_CMDLINE_LINUX. So final line may look like below: GRUB_CMDLINE_LINUX=”vconsole.keymap=us crashkernel=auto vconsole.font=latarcyrheb-sun16 rhgb quiet net.ifnames=0 biosdevname=0″ 3. grub2-mkconfig -o /boot/grub2/grub.cfg 4. rename /etc/sysconfig/network-scripts/ifcfg-en**** to /etc/syconfig/network-scripts/ifcfg-eth0 5. In ifcfg-eth0 file Change NAME=en*** to NAME=eth0 6. reboot

Pluggable Authentication Module (PAM)

Please note these notes are based on CentOS/RHEL 5 – What is PAM ? The glue between authentication methods [eg one-time pwds, kerberos, smart cards] and applications requiring authentication services [eg. ftpd, sshd, imapd] etc It is another layer on 1st-Level defense in Linux. – The 4 directories we are concerned with: /lib/libpam*      [3 files…