Kerberos setup in Cloudera Hadoop

Reference: Cloudera Security manual .pdf – CDH 5.15 on Cloudera Documentation website   Environment: Cloudera CDH 5.15 on Centos 7 MIT KDC Kerberos   Setting up Kerberos in Cloudera CDH is somewhat tricky. The above blog is a good step by step way to setup. Also refer to the official Cloudera Security … Continue reading Kerberos setup in Cloudera Hadoop

Virtualbox VM setups.

Virtualbox network setup for internet access: Generally the following table gives the connectivity for different Virtualbox Network adapters. Sometimes it is possible the Bridged network wont get an ipv4 address and cannot connect to internet. Then we have to setup both a NAT and a Host-only adapter network. The requirement is: Host is Windows 10, … Continue reading Virtualbox VM setups.

Upgrade MySQL 5.6 to 5.7 on Centos 7

Reference: 1. # service mysql stop 2. Important backup your databases before upgrade. Create a backup of the original MySQL data. $ cp /var/lib/mysql /var/lib/mysql.original 2. Download the MySQL 5.7 RPM $ wget -P /tmp/ 3. Remove the MySQL-Community RPM that contains MySQL 5.6 $ yum remove mysql-community-release 4. Install the MySQL 5.7 RPM … Continue reading Upgrade MySQL 5.6 to 5.7 on Centos 7

PostgreSQL notes

In Ubuntu, the server is run as a service called postgresql (configured in /etc/init.d/postgresql). The postgresql service is started automatically upon startup. Like all other services, you could: $ sudo service postgresql stop // Stop the service $ sudo service postgresql start // Start the service $ sudo service postgresql restart // Stop and restart the service $ sudo service postgresql reload … Continue reading PostgreSQL notes

Enable SSH login to Ubuntu by root user

In Ubuntu 16.04 by default root login by SSH is blocked for security reason. To enable root to login by SSH we have to update the ssh configuration. NOTE: This may make your server insecure for hackers so just enable root login temporarily if needed. /etc/ssh# ssh root Permission denied (publickey). Next edit the file:  /etc/ssh# vi sshd_config Change the following … Continue reading Enable SSH login to Ubuntu by root user

Ansible script examples

EXAMPLE: Restart NTP daemon in Linux First create the playbook pbntprestart.yml as below and run using this command. The cdhservers is where you define all your hostnames. $ ansible-playbook pbntprestart.yml -u root -k The content of pbntprestart.yml  is below: $ cat pbntprestart.yml --- - hosts: cdhservers tasks: - name: NTPRESTART shell: service ntpd restart register: out1 … Continue reading Ansible script examples

Let’s Encrypt free SSL certificate authority (CA)

Let’s Encrypt is a free, automated, and open certificate authority (CA), run for the public’s benefit. It is a service provided by the Internet Security Research Group (ISRG). The key principles behind Let’s Encrypt are: Free: Anyone who owns a domain name can use Let’s Encrypt to obtain a trusted certificate at zero cost. Automatic: Software running on … Continue reading Let’s Encrypt free SSL certificate authority (CA)