C
Charlie Barajas
Guest
Azure Network Security Groups: Your Cloud's First Line of Defense 
Azure Network Security Groups (NSGs) are essential building blocks for securing your cloud infrastructure. Think of them as virtual firewalls that control network traffic to and from your Azure resources!
What Are Network Security Groups?
NSGs contain security rules that allow or deny inbound and outbound network traffic based on:
Source and destination IP addresses
Port numbers
Protocol (TCP, UDP, ICMP)
Direction (inbound/outbound)
Key Features
Granular Control
Filter traffic at the subnet or network interface level
Apply different rules to different resources
Create custom security policies
Default Rules
Every NSG comes with built-in rules:
Allow inbound traffic within VNet
Allow inbound traffic from Azure Load Balancer
Deny all other inbound traffic
Allow all outbound traffic to internet
Stateful Filtering
Automatically allows return traffic for established connections
No need to create separate rules for response traffic
Best Practices
Principle of Least Privilege
Start with deny-all and only allow what's necessary
Regularly audit and remove unused rules
Use service tags instead of IP ranges when possible
Use Service Tags
Popular service tags include:
Internet
VirtualNetwork
Storage
SQL
AzureLoadBalancer
Naming Conventions
Use descriptive names like:
Allow-HTTP-Inbound
Deny-SSH-Internet
Allow-DB-Subnet
Common Use Cases
Web Applications
Priority 100: Allow HTTP (80) from Internet
Priority 110: Allow HTTPS (443) from Internet
Priority 120: Allow SSH (22) from Admin subnet only
Priority 130: Deny all other inbound traffic
Database Tier
Priority 100: Allow SQL (1433) from App subnet only
Priority 110: Allow management from Admin subnet
Priority 120: Deny all internet access
Management Access
Priority 100: Allow RDP (3389) from corporate IP ranges
Priority 110: Allow SSH (22) from jump box subnet
Priority 120: Block all other management protocols
Advanced Features
Application Security Groups (ASGs)
Group VMs by application role
Simplify rule management
Make policies more readable
Flow Logs
Monitor and analyze network traffic
Troubleshoot connectivity issues
Detect security threats
Augmented Security Rules
Use multiple IP ranges in single rule
Combine service tags with IP addresses
More flexible rule definitions
Monitoring & Troubleshooting
Key Metrics to Watch
Packets blocked/allowed
Security rule hit counts
Flow log analysis
Common Issues
Conflicting rule priorities
Overly broad allow rules
Missing return traffic rules for stateless protocols
Security Tips
Regular Audits
Review rules quarterly
Remove unused/outdated rules
Check for overly permissive access
Documentation
Document rule purposes
Maintain change logs
Create architecture diagrams
Testing
Test rules in development first
Use Network Watcher for validation
Monitor after changes
Conclusion
Network Security Groups are fundamental to Azure security architecture. When properly configured with the principle of least privilege, they provide robust protection for your cloud resources while maintaining operational flexibility.
Remember: Security is not a one-time setupβit's an ongoing process!
Ready to secure your Azure environment? Start with NSGs and build a strong foundation for your cloud security!
Continue reading...
Azure Network Security Groups (NSGs) are essential building blocks for securing your cloud infrastructure. Think of them as virtual firewalls that control network traffic to and from your Azure resources!
What Are Network Security Groups?
NSGs contain security rules that allow or deny inbound and outbound network traffic based on:
Source and destination IP addresses Port numbers Protocol (TCP, UDP, ICMP) Direction (inbound/outbound)Key Features
Granular ControlFilter traffic at the subnet or network interface level
Apply different rules to different resources
Create custom security policies
Default RulesEvery NSG comes with built-in rules:
Allow inbound traffic within VNet Allow inbound traffic from Azure Load Balancer Deny all other inbound traffic Allow all outbound traffic to internet Stateful FilteringAutomatically allows return traffic for established connections
No need to create separate rules for response traffic
Best Practices
Principle of Least PrivilegeStart with deny-all and only allow what's necessary
Regularly audit and remove unused rules
Use service tags instead of IP ranges when possible
Use Service TagsPopular service tags include:
Internet
VirtualNetwork
Storage
SQL
AzureLoadBalancer
Naming ConventionsUse descriptive names like:
Allow-HTTP-Inbound
Deny-SSH-Internet
Allow-DB-Subnet
Common Use Cases
Web ApplicationsPriority 100: Allow HTTP (80) from Internet
Priority 110: Allow HTTPS (443) from Internet
Priority 120: Allow SSH (22) from Admin subnet only
Priority 130: Deny all other inbound traffic
Database TierPriority 100: Allow SQL (1433) from App subnet only
Priority 110: Allow management from Admin subnet
Priority 120: Deny all internet access
Management AccessPriority 100: Allow RDP (3389) from corporate IP ranges
Priority 110: Allow SSH (22) from jump box subnet
Priority 120: Block all other management protocols
Advanced Features
Application Security Groups (ASGs)Group VMs by application role
Simplify rule management
Make policies more readable
Flow LogsMonitor and analyze network traffic
Troubleshoot connectivity issues
Detect security threats
Augmented Security RulesUse multiple IP ranges in single rule
Combine service tags with IP addresses
More flexible rule definitions
Monitoring & Troubleshooting
Key Metrics to WatchPackets blocked/allowed
Security rule hit counts
Flow log analysis
Common Issues Conflicting rule priorities Overly broad allow rules Missing return traffic rules for stateless protocolsSecurity Tips
Regular Audits
Review rules quarterly
Remove unused/outdated rules
Check for overly permissive access
Documentation
Document rule purposes
Maintain change logs
Create architecture diagrams
Testing
Test rules in development first
Use Network Watcher for validation
Monitor after changes
Conclusion
Network Security Groups are fundamental to Azure security architecture. When properly configured with the principle of least privilege, they provide robust protection for your cloud resources while maintaining operational flexibility.
Remember: Security is not a one-time setupβit's an ongoing process!
Ready to secure your Azure environment? Start with NSGs and build a strong foundation for your cloud security!
Continue reading...
