Day 3 – Setting Up Virtual Machines Manually

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Objective

Today is my third day of learning DevOps, and I focused on setting up virtual machines manually and accessing them remotely via SSH. I used VirtualBox to install both Ubuntu Server 22.04 and CentOS 7, which helped me understand more about Linux system setup and networking.

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🧱 What I Did

1. Downloaded ISO Images

• Ubuntu Server 22.04

• CentOS 7

2. Created Virtual Machines in VirtualBox

• Allocated 2 GB RAM and 1-2 CPUs

• Created a virtual hard disk (20 GB)

• Mounted the ISO

• Installed the OS manually (partitioning, hostname, user setup)

3. Enabled Networking

• Set network adapter to Bridged Adapter for each VM

• Ensured the VM receives an IP address via DHCP

4. Installed OpenSSH Server

Ubuntu:

SSH is usually installed by default. If not:

sudo apt update
sudo apt install openssh-server

FOR CentOS:

bashCopyEditsudo yum install openssh-server
sudo systemctl enable sshd --now

5. Found IP Address of VM

ip a

Or used:

ip addr show

6. Connected via SSH from my host machine

ssh username@ip-address

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🛠️ Problems I Faced & Fixed

• 🔐 Couldn't SSH into CentOS: SSH service was not running. Fixed it with:

    bashCopyEditsudo systemctl enable sshd --now
  

• 🌐 No IP Address on CentOS: Used nmtui to activate the network interface.

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💡 Key Takeaways

• Manual VM installation improves understanding of OS internals.

• SSH is a critical tool for remote management.

• Networking setup (bridged/NAT + port forwarding) is crucial when working with VMs.

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🔮 What's Next

Tomorrow, I plan to explore shared folder setup, hostname configuration, or maybe even automate VM provisioning using Vagrant.