Distributed systems are essential for modern computing, allowing multiple computers to work together to achieve common goals. These systems improve performance, scalability, and reliability by distributing tasks across multiple nodes. In the Linux environment, setting up distributed systems can be highly efficient due to the robust tools and open-source software available. This article will guide you through the process of setting up a distributed system on Linux, using practical examples and commands.

Examples:

1. Setting Up SSH for Secure Communication:

   SSH (Secure Shell) is crucial for secure communication between nodes in a distributed system.

   # Install SSH server
   sudo apt-get install openssh-server
   
   # Start the SSH service
   sudo systemctl start ssh
   
   # Enable SSH to start on boot
   sudo systemctl enable ssh
   
   # Generate SSH keys on the client
   ssh-keygen -t rsa -b 2048
   
   # Copy the public key to the server
   ssh-copy-id user@server_ip

2. Using NFS for Shared Storage:

   Network File System (NFS) allows multiple nodes to share storage resources.

   # Install NFS server on the server node
   sudo apt-get install nfs-kernel-server
   
   # Create a directory to share
   sudo mkdir -p /mnt/shared
   
   # Set permissions
   sudo chown nobody:nogroup /mnt/shared
   
   # Configure the NFS exports
   echo "/mnt/shared *(rw,sync,no_subtree_check)" | sudo tee -a /etc/exports
   
   # Export the shared directory
   sudo exportfs -a
   
   # Install NFS client on the client node
   sudo apt-get install nfs-common
   
   # Mount the shared directory on the client
   sudo mount server_ip:/mnt/shared /mnt/shared

3. Setting Up a Distributed Database with MongoDB:

   MongoDB can be configured for distributed data storage using replica sets and sharding.

   # Install MongoDB on each node
   sudo apt-get install -y mongodb
   
   # Configure replica sets
   sudo nano /etc/mongodb.conf
   # Add the following lines:
   # replication:
   #   replSetName: "rs0"
   
   # Start MongoDB service
   sudo systemctl start mongodb
   
   # Initialize the replica set
   mongo --eval 'rs.initiate()'
   
   # Add members to the replica set
   mongo --eval 'rs.add("node2:27017")'
   mongo --eval 'rs.add("node3:27017")'
   
   # Configure sharding
   mongo --eval 'sh.addShard("rs0/node1:27017")'
   mongo --eval 'sh.addShard("rs0/node2:27017")'
   mongo --eval 'sh.addShard("rs0/node3:27017")'

4. Using Apache Kafka for Distributed Messaging:

   Apache Kafka is a distributed streaming platform that can handle real-time data feeds.

   # Download and extract Kafka
   wget https://downloads.apache.org/kafka/2.8.0/kafka_2.13-2.8.0.tgz
   tar -xzf kafka_2.13-2.8.0.tgz
   cd kafka_2.13-2.8.0
   
   # Start Zookeeper (required by Kafka)
   bin/zookeeper-server-start.sh config/zookeeper.properties
   
   # Start Kafka broker
   bin/kafka-server-start.sh config/server.properties
   
   # Create a Kafka topic
   bin/kafka-topics.sh --create --topic test --bootstrap-server localhost:9092 --replication-factor 1 --partitions 1
   
   # Produce messages to the topic
   bin/kafka-console-producer.sh --topic test --bootstrap-server localhost:9092
   
   # Consume messages from the topic
   bin/kafka-console-consumer.sh --topic test --from-beginning --bootstrap-server localhost:9092