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In today's era of rampant cyber threats and eavesdropping, securing communication between cluster nodes is imperative to maintain data integrity and confidentiality. In this article, we will focus on configuring encrypted communication between nodes in a cluster using Corosync on the CentOS 7 operating system, which represents one of the proven solutions for ensuring the security of cluster messages.

Prerequisites

Before we begin, ensure that:

• CentOS 7 is installed on all cluster nodes.
• Corosync and Pacemaker are installed on all nodes.
• You have root access or sudo access on all nodes.

Installation and Basic Corosync Configuration

1. Install Packages

   Install Corosync and Pacemaker on all cluster nodes using the following command:

   sudo yum install corosync pacemaker pcs
   

2. Node Authentication Configuration

   On one of the nodes, execute the following command to set a password for the hacluster user. This password will enable nodes to authenticate with each other.

   sudo passwd hacluster
   

   Then, use the pcs tool to propagate the password to all nodes in the cluster:

   sudo pcs cluster auth node1 node2 -u hacluster -p password --force
   

   Replace node1 node2 with the actual hostnames of your nodes.

Setting up Encrypted Communication

1. Key Generation and Distribution

   Corosync utilizes symmetric encryption for communication between nodes. The first step is to generate a shared secret key.

   Generate the key on one of the nodes using the corosync-keygen tool, which is part of the Corosync package.

   sudo corosync-keygen
   

   After generating the key, copy it to all other cluster nodes into the /etc/corosync/ directory.

2. Configuring Corosync for Encrypted Communication

   In the /etc/corosync/corosync.conf file on all nodes, make the following changes:

   • Ensure that the totem section contains the following lines to enable encryption:

     secauth: on
     crypto_cipher: aes256
     crypto_hash: sha256
     

     This ensures the use of strong encryption and hashing.

3. Restart Services

   After completing the configuration on all nodes, restart the Corosync and Pacemaker services to apply the changes:

   sudo systemctl restart corosync
   sudo systemctl restart pacemaker
   

Verification and Testing

To verify that communication between nodes is encrypted, you can use the tcpdump tool to capture network traffic between nodes and subsequently verify whether the data is encrypted.

Setting up encrypted communication between nodes in a cluster using Corosync on CentOS 7 is a crucial step in securing your cluster. Follow the steps outlined above to ensure that your cluster communication is protected against unauthorized eavesdropping and attacks.