Exercise: Setting up Virtual Machines (VMs) in the Cloud

Prerequisites

• You should already have created a Virtual Machine

Step 1: Connect to your VM

Use SSH to connect to your VM. You can find the public IP address of your VM in the cloud provider's dashboard.

ssh root@VM_IP_ADDRESS

Replace VM_IP_ADDRESS with the actual IP address of your VM.

Verify that you are connected to the VM by checking the hostname:

hostname

Step 2: Update the system

Before installing any software, it's a good practice to update the package lists and upgrade the installed packages:

sudo apt update

This command updates the package lists for upgrades and new packages. After that, you can upgrade the installed packages:

sudo apt upgrade -y

This command upgrades all the installed packages to their latest versions. The -y flag automatically answers "yes" to any prompts during the upgrade process.

Updating the system ensures that you have the latest security patches and software updates, which is crucial for maintaining the security and performance of your VM.

Update time zone To set the correct time zone on your VM, you can use the timedatectl command. First, list the available time zones:

timedatectl

Then, set the desired time zone (replace Your/Timezone with the appropriate time zone):

sudo timedatectl set-timezone Europe/Copenhagen

Step 3: Install packages

Now that your system is updated, you can perform basic Linux administration tasks such as installing software, managing services, and monitoring system resources.

To install a software package, use the apt install command. For example, to install pwgen, run:

sudo apt install pwgen net-tools -y

This command installs the pwgen and net-tools packages, which are a password generator and network tools respectively.

To check the location of an installed package, you can use the which command:

which pwgen

This command will show the path to the pwgen executable, confirming that it is installed correctly.

Step 4: Managing processes

The simplest way to check if a server is doing well is to check the running processes. You can use the htop command to view a real-time list of running processes and their resource usage:

htop

To exit htop, press q.

This shows you the CPU and memory usage of each process, as well as other details such as the process ID (PID) and the command that started the process. You can use the arrow keys to navigate through the list of processes.

Each process has a unique PID. If you want to stop a process, you can use the kill command followed by the PID of the process you want to stop. For example, if you want to stop a process with PID 1234, you would run:

kill -9 1234

This command forces the process to stop immediately. Use this command with caution, as it does not allow the process to clean up resources or save its state before exiting.

You can also use the ps command to view a snapshot of the current processes. For example, to view all running processes, you can run:

ps aux

This command lists all running processes along with their details such as the user, PID, CPU and memory usage, and the command that started the process.

The options used in the ps aux command are:

• a: Show processes for all users.
• u: Display the process's user/owner.
• x: Show processes that do not have a controlling terminal for the current user.
• f: Show a full-format listing, which shows the hierarchical relationship between processes (i.e. which processes have been started by which other processes).

Step 5: Monitoring network connections

You can monitor network connections using the netstat command. This command shows you all active network connections and their associated processes. To use netstat, run:

netstat -atlpn

The options used in the netstat -atlpn command are:

• a: Show all active connections and listening ports.
• t: Show TCP connections.
• l: Show only listening ports.
• p: Show the PID and name of the program to which each socket belongs.
• n: Show numerical addresses instead of resolving hostnames.

In this example, we can see that the program sshd (which is the SSH process) is listening on port 22 for incoming connections (the Local Address column shows 0.0.0.0:22). This means that the SSH service is running and ready to accept connections on port 22. Furthermore, we can see three different connections to the SSH service from different IP addresses (the Foreign Address column shows the IP addresses of the clients that are connected to the SSH service). This indicates that there are currently three active SSH sessions on the server.