Setting Up PostgreSQL on Your Linux System

PostgreSQL, also known as "Postgres," is a highly extensible and standards-compliant object-relational database management system (ORDBMS). It's renowned for its robustness, ACID-compliance, advanced features like multiversion concurrency control (MVCC), and a wide array of indexing methods, functions, and more. This guide will walk you through configuring your YUM repository, installing PostgreSQL, and setting up a basic database schema.

Step 1: Configure Your YUM Repository

Locate and Edit Your Distributions .repo File:

• Fedora: Edit /etc/yum.repos.d/fedora.repo and /etc/yum.repos.d/fedora-updates.repo, specifically the [fedora] sections.
• CentOS: Edit /etc/yum.repos.d/CentOS-Base.repo, focusing on the [base] and [updates] sections.
• Red Hat: Edit /etc/yum/pluginconf.d/rhnplugin.conf and look for the [main] section.

Append the Exclude Line: To each of the sections identified above, append the following line to prevent the default PostgreSQL package from being installed, as it may be outdated:

exclude=postgresql*

Step 2: Download and Install the PGDG RPM File

PGDG File: PostgreSQL Global Development Group (PGDG) provides an optimized and more up-to-date version of PostgreSQL.

1. Find the Correct RPM:

   • Browse PostgreSQL's YUM repository to find the RPM suitable for your distribution, architecture, and desired PostgreSQL version.

2. Download the RPM:

   • For example, to install PostgreSQL 9.3 on CentOS 6 64-bit:

   curl -O http://yum.postgresql.org/9.3/redhat/rhel-6-x86_64/pgdg-centos93-9.3-1.noarch.rpm
   

3. Install the RPM Distribution:

   rpm -ivh pgdg-centos93-9.3-1.noarch.rpm
   

Step 3: Install PostgreSQL

List Available Packages:

yum list postgres*

Install PostgreSQL Server:

• For a basic PostgreSQL 9.3 server installation:

  yum install postgresql93-server
  

Step 4: Accessing PostgreSQL

Switch to the PostgreSQL User:

su - postgres

Start Using PostgreSQL:

psql

You're now in the PostgreSQL command line. Here you can manage databases, execute SQL queries, and more.

Step 5: Setting Up a Basic Database Schema

Create a Schema Called test:

CREATE SCHEMA test;

Create a Role (User) with Password:

CREATE USER xxx PASSWORD 'yyy';

Grant Privileges on New Schema to New Role:

GRANT ALL ON SCHEMA test TO xxx;

Grant Privileges on Tables in the New Schema to the New Role:

GRANT ALL ON ALL TABLES IN SCHEMA test TO xxx;

Step 6: Disconnecting

Exit psql:

\q

Conclusion

Congratulations! You've successfully set up PostgreSQL on your Linux system. You've also created your first schema and user with privileges. PostgreSQL is a powerful tool with many more capabilities and features to explore. As you become more familiar with its workings, you'll be able to leverage its full potential in managing and analyzing your data effectively. Don't forget to regularly check for updates and maintain your PostgreSQL installation to ensure security and performance.

Mastering Puppet: A Guide to Configuring the Puppet Master and Client

Puppet is a powerful configuration management tool that automates the process of managing your infrastructure. Setting up a Puppet Master and its clients can seem daunting, but with this guide, you'll be equipped to handle the initial configuration with ease. This blog will walk you through the steps needed to set up a Puppet Master and client, ensuring a smooth and secure connection between them.

Step 1: Initial Setup for Both Master and Client

Downloading and Installing Needed RPM

Before you begin, ensure that both the Master and the client machines have the necessary RPM installed. This can be done by running:

rpm -ivUh http://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm

This command will install the EPEL (Extra Packages for Enterprise Linux) repository, providing additional packages for your setup.

Step 2: Installing the Puppet Server and Client

Master: Installing Puppet Server

On your Master machine, install the Puppet Server with Yum:

yum install puppet-server

Client: Installing Puppet

On the client machine, install the Puppet client software:

yum install puppet

Step 3: Configuring Hostnames and Network

Ensure that the Master and client can communicate with each other by setting up the hostnames correctly.

Edit the Hosts File

Add the following entries to the /etc/hosts file on both the Master and client:

xxx.xxx.xxx.xxx master.puppet.com

xxx.xxx.xxx.xxx client.puppet.com

Replace xxx.xxx.xxx.xxx with the appropriate IP addresses.

Test the Connection

Test the connectivity between the Master and client using the ping command:

ping -c 3 client.puppet.com

ping -c 3 master.puppet.com

Step 4: Setting Up Iptables

For secure communication, you need to ensure that the correct port is open on both the Master and client.

Modify Iptables Rules

You can either disable Iptables or open port 8140, which Puppet uses for communication:

iptables -A INPUT -p tcp --dport 8140 -m state --state NEW,ESTABLISHED -j ACCEPT

Step 5: Starting the Puppet Master Server

With the configurations set, it's time to start the Puppet Master.

Start the Server

On the Master machine, start the Puppet Master service:

/etc/init.d/puppetmaster restart

Step 6: Client Certificate Signing

Puppet uses a certificate-based authentication system. The client will request a certificate from the Master, which needs to be signed.

Check for Signed Certificates

From the client machine, initiate a certificate signing request:

puppetd --server=master.puppet.com --waitforcert 60 --test

Sign the Client's Certificate

On the Master, list all unsigned certificates:

puppetca --list

Sign the client's certificate:

puppetca --sign client.puppet.com

Step 7: Creating Configuration for Clients

With the infrastructure in place, you'll now need to define the desired state of your client systems in the Puppet Master.

Edit the Manifest File

Add configurations to /etc/puppet/manifests/site.pp on the Master. Here's a sample configuration:

# Create "/tmp/testfile" if it doesn't exist.

file { "/tmp/outside":

ensure => present,

mode => 644,

owner => root,

group => root

}

class test_class {

file { "/tmp/testfile":

ensure => present,

mode => 644,

owner => root,

group => root

}

}

package {

'httpd':

ensure => installed }

service {

'httpd':

ensure => true,

enable => true,

require => Package['httpd']

}

# tell puppet on which client to run the class

node client {

include test_class

}

Conclusion

Congratulations! If you've followed these steps without error, your Puppet Master and client are now configured and communicating securely. With your infrastructure now under Puppet's management, you're set to automate your configurations, ensuring consistency and reliability across your environment. Remember, Puppet is incredibly powerful and flexible. Continue exploring its capabilities to fully harness its potential in managing your infrastructure.

Building a Custom NAT Server on AWS: A Step-by-Step Guide

Network Address Translation (NAT) servers are essential components in a cloud infrastructure, allowing instances in a private subnet to connect to the internet or other AWS services while preventing the internet from initiating a connection with those instances. This blog provides a detailed guide on setting up a NAT server from scratch in an AWS cloud environment.

Step 1: Launching an AWS Instance

Start a t1.micro instance:

• Navigate to the AWS Management Console.
• Select the EC2 service and choose to launch a t1.micro instance.
• Pick an Amazon Machine Image (AMI) that suits your needs (commonly Amazon Linux or Ubuntu).
• Configure instance details ensuring it's in the same VPC as your private subnet but in a public subnet.

Step 2: Configuring the Instance

Disable "Change Source / Dest Check":

• Right-click on the instance from the EC2 dashboard.
• Navigate to "Networking" and select "Change Source / Dest Check."
• Disable this setting to allow the instance to route traffic not specifically destined for itself.

Security Group Settings:

• Ensure the Security Group associated with your NAT instance allows the necessary traffic.
• Typically, it should allow inbound traffic on ports 80 (HTTP) and 443 (HTTPS) for updates and patches.

Step 3: Configuring the NAT Server

Access your instance via SSH and perform the following configurations:

Enable IP Forwarding:

1. Edit the /etc/sysctl.conf file to enable IP forwarding. This setting allows the instance to forward traffic from the private subnet to the internet.

   sed -i "s/net.ipv4.ip_forward.*/net.ipv4.ip_forward = 1/g" /etc/sysctl.conf
   

2. Activate the change immediately:

   echo 1 > /proc/sys/net/ipv4/ip_forward
   

3. Confirm the change:

   cat /etc/sysctl.conf | grep net.ipv4.ip_forward
   

   Expected output: net.ipv4.ip_forward = 1

Configure iptables:

1. Set up NAT using iptables to masquerade outbound traffic, making it appear as if it originates from the NAT server:

   iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
   

   This command routes all connections reaching eth0 (the primary network interface) to all available paths.

2. Allow traffic on ports 80 and 443 for updates and external access:

   iptables -A INPUT -m state --state NEW -p tcp --dport 80 -j ACCEPT
   iptables -A INPUT -m state --state NEW -p tcp --dport 443 -j ACCEPT
   iptables -A FORWARD -i eth0 -j ACCEPT
   

Step 4: Routing Configuration

Configure Route Tables:

• In the AWS Console, go to the VPC Dashboard and select Route Tables.
• Modify the route table associated with your private subnet:
  • Add a route where the destination is 0.0.0.0/0 (representing all traffic), and the target is the instance ID of your NAT server.
• Modify the route table associated with your NAT instance:
  • Ensure there's a route where the destination is 0.0.0.0/0, and the target is the internet gateway of your VPC.

Conclusion

With these steps, you've successfully created a NAT server in your AWS environment, allowing instances in a private subnet to securely access the internet for updates and communicate with other AWS services. This setup is crucial for maintaining a secure and efficient cloud infrastructure. Always monitor and maintain your NAT server to ensure it operates smoothly and securely. Currently there are managed NAT server services from AWs which we can use for production grade environments.