Azure NSG Routes

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 setup—it's an ongoing process! 🔄

Ready to secure your Azure environment? Start with NSGs and build a strong foundation for your cloud security! 💪