Spotlight
PAGE: https://alison.com/course/advanced-esxi-5-0-security-server-and-vm-monitoring
PROMISE: Harden ESXi hosts and clarify VM security posture basics for monitoring workflows
WHO: System administrators managing ESXi infrastructure who need foundational hardening and VM security knowledge
WHYNOW: The course provides current CPD-accredited content that maps directly to existing vSphere monitoring and host configuration tasks
DESC: Learn about the Virtual Machine Monitoring tools which provide extensive metric data to monitor your virtual machine servers and guest virtual machines.
BEFORE: ESXi host firewall settings are unverified and possibly misconfigured
BEFORE: VM resource limits are confused, leading to inaccurate performance monitoring
BEFORE: Host patching is manual and lacks a structured update workflow
AFTER: ESXi firewall rules are documented and aligned with security policy
AFTER: CPU and memory settings are clearly distinguished in monitoring and capacity planning
AFTER: Hypervisor updates follow a defined, auditable process via Update Manager
GAIN: A clear procedure to configure and validate ESXi firewall settings
GAIN: The ability to correctly interpret and manage CPU versus memory resource settings
GAIN: A structured method to manage ESXi host updates and patch cycles
STEP: You cannot verify if vSphere firewall rules are blocking malicious VM traffic || State the processes involved in ESXi Firewall Configuration via vSphere Client || Review and document host firewall rules to ensure only necessary ports remain open on the ESXi hypervisor
STEP: VM resource spikes are misdiagnosed because CPU and memory limits are not clearly separated || Distinguish between CPU Resource Settings and Memory Resource Settings || Apply correct resource constraints in vSphere to isolate performance issues and prevent noisy neighbor scenarios
STEP: You lack a baseline for what resource requirements mean when migrating VMs between hosts || List the requirements of common resources on Source and Destination ESX/ESXi Hosts || Compare host capabilities before movement to maintain stability and align monitoring thresholds with actual load
STEP: Security updates for the hypervisor are not scheduled or verified properly || Explain the process in Update Manager vSphere Client Plugin || Use Update Manager workflows to patch hosts systematically and reduce the window of exposure to known vulnerabilities
NOTFOR: Readers who need detailed certificate lifecycle management or TLS validation tooling
NOTFOR: Teams seeking advanced network intrusion detection or specific malware analysis modules
FACT: Average duration: 6-10 Hours (Contains Video)
FACT: CPD-accredited certificate available
FACT: Intermediate level
COVERS: State the processes involved in ESXi Firewall Configuration via vSphere Client
COVERS: Distinguish between CPU Resource Settings and Memory Resource Settings
COVERS: List the requirements of common resources on Source and Destination ESX/ESXi Hosts
COVERS: Explain the process in Update Manager vSphere Client Plugin
COVERS: Identify the best technologies for achieving your backup and disaster recovery goals
COVERS: Recognize the difference between backup and disaster recovery
COVERS: Identify key concepts that are critical for developing effective strategies for backup and disaster recovery
COVERS: Network Security
COVERS: Cybersecurity
COVERS: Linux
COVERS: Computer Science
MODULE: Security and Permissions || Controlling User Access and Passwords | ESXi Active Directory (AD) Integration | Managing Firewalls | Secure Shell (SSH) Access | The root Account | VMsafe and vShield
MODULE: Server and VM Monitoring || Optimizing Resources | Performance Monitoring | Configuring Alarms | ESXi and vCenter Logs
MODULE: Advanced ESXi and vCenter Server Management || Storage Views & Topology Maps | Storage vMotion | Configuring vMotion | Distributed Resource Scheduler (DRS) Cluster | Datastore Clusters & Storage DRS (SDRS) | Resource Pools and Monitoring | Host Profiles | Linked Mode Group of vCenter Servers | vSphere Storage Appliance (VSA)
MODULE: Patching and Upgrading ESXi || Patching ESXi Standalone Hosts | Patching with Update Manager | Upgrades and Migrations
MODULE: Disaster Recovery and Backup || Site Recovery Manager (SRM) | High Availability (HA) | Virtual Machine Fault Tolerance | Microsoft Clustering | Backup Strategies | VMware Data Recovery | Third Party Backups
What you are probably seeing
Your certificate monitoring tool displays a new TLS certificate for your domain that you did not request or approve for issuance.
The certificate metadata shows an unexpected issuer or a validity period that does not align with your internal issuance logs.
Why it happens
Threat actors exploit vulnerabilities in Certificate Authority systems to obtain valid-looking certificates for domains they do not control.
Standard trust stores may validate these forged documents because they follow the correct cryptographic format and chain of trust.
What changed recently
2026-10-07 · Google warns of unauthorized TLS certificates for its own and other major domains 
arstechnica.com/security/202…
Ars Technica reports how large services were compromised:
• Counterfeit TLS certificates obtained for Google and other large services
• Unauthorized certificates affect major domains, not just individual users
Source: bluesky
Step by step
1. Cross-reference all active certificates in your inventory against your internal PKI issuance logs to identify discrepancies.
2. Configure your monitoring tool to alert on any certificate for your domain that is not signed by your approved internal CA.
3. Enforce a strict maximum validity period in your policy to limit the window of opportunity for attackers.
4. Review the Serial Number and Issuer fields of any unexpected certificates to determine the source of the compromise.
5. Revoke and replace any unauthorized certificates immediately and update your trust anchors to exclude the compromised CA if necessary.
Ways to go further
Start here: Advanced ESXi 5.0 – Security, Server and VM Monitoring For when you are evaluating ESXi server hardening and VM security posture. Open the free course on Alison ↗
Better fit: Security Guarding, CCTV Monitoring and Door Supervision For when you want to audit physical and logical access control gaps. Open the free course on Alison ↗
Best when: Fundamentals of Prometheus Software – Performance Monitoring for IT Systems For when you need to monitor certificate issuance across large-scale infrastructure. Open the free course on Alison ↗
Affiliate links: CHEAPUNO may earn a commission if you buy through them, at no extra cost to you.
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