Update tech_docs/cloud/aws_notes.md

tech_docs/cloud/aws_notes.md

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+Here’s a **30-day hands-on exercise plan** to build muscle memory for hybrid/multi-cloud networking, using free or low-cost tools. Start with foundational drills and progress to real-world scenarios:
+
+---
+
+### **Week 1: Core Hybrid Connectivity**
+#### **Exercise 1: Site-to-Site VPN (AWS ↔ On-Prem)**
+**Goal**: Simulate a branch office connection.  
+**Steps**:  
+1. **AWS Side**:  
+   ```bash
+   # Create a Virtual Private Gateway (VGW)
+   aws ec2 create-vpn-gateway --type ipsec.1 --tag-specifications 'ResourceType=vgw,Tags=[{Key=Name,Value=Lab-VGW}]'
+   ```
+2. **On-Prem Side**:  
+   - Use a **free VPN appliance** (Sophos XG Home Edition or pfSense).  
+   - Configure IPsec tunnel to AWS VGW using [AWS-generated config](https://docs.aws.amazon.com/vpn/latest/s2svpn/SetUpVPNConnections.html).  
+**Validation**:  
+   ```bash
+   # Check tunnel status
+   aws ec2 describe-vpn-connections --query 'VpnConnections[].VgwTelemetry[].Status'
+   ```
+
+#### **Exercise 2: Direct Connect BGP Tuning**
+**Goal**: Optimize BGP for failover.  
+**Steps**:  
+1. Simulate Direct Connect with **AWS VPN + BGP**:  
+   ```bash
+   aws ec2 create-vpn-connection \
+     --type ipsec.1 \
+     --customer-gateway-id <cgw-id> \
+     --vpn-gateway-id <vgw-id> \
+     --options "{\"TunnelOptions\": [{\"TunnelInsideCidr\": \"169.254.100.0/30\", \"BGPConfig\": {\"Asn\": 65001}}]}"
+   ```
+2. Adjust BGP timers:  
+   ```bash
+   # On Linux (FRRouting)
+   vtysh -c "configure terminal" -c "router bgp 65001" -c "timers bgp 10 30"
+   ```
+**Pro Tip**: Use `tcpdump` to verify BGP keepalives:  
+```bash
+sudo tcpdump -i eth0 'tcp port 179 and (tcp-syn|tcp-ack)!=0' -vv
+```
+
+---
+
+### **Week 2: Multi-Cloud Networking**
+#### **Exercise 3: AWS TGW ↔ Azure vWAN**
+**Goal**: Connect AWS and Azure without public internet.  
+**Steps**:  
+1. **AWS Side**:  
+   ```bash
+   # Create Transit Gateway attachment
+   aws ec2 create-transit-gateway-vpc-attachment \
+     --transit-gateway-id tgw-123 \
+     --vpc-id vpc-abc \
+     --subnet-ids subnet-456
+   ```
+2. **Azure Side**:  
+   ```powershell
+   # Create Virtual WAN connection
+   New-AzVirtualHubVnetConnection -ResourceGroupName "rg1" -VirtualHubName "hub1" -Name "aws-conn" -RemoteVirtualNetworkId "/subscriptions/.../vnet-xyz"
+   ```
+**Validation**:  
+   - Ping an Azure VM from an AWS EC2 instance over private IPs.  
+
+#### **Exercise 4: Google Cloud Interconnect**
+**Goal**: Set up VLAN attachment between GCP and AWS.  
+**Steps**:  
+1. In **GCP Console**:  
+   - Create a **Cloud Interconnect VLAN Attachment**.  
+2. **AWS Side**:  
+   - Configure a **Direct Connect Gateway**.  
+**Pro Tip**: Use `gcloud` to verify:  
+```bash
+gcloud compute interconnects attachments describe aws-attachment --region us-central1
+```
+
+---
+
+### **Week 3: Zero Trust & Security**
+#### **Exercise 5: Replace VPN with Tailscale**
+**Goal**: Implement identity-based access.  
+**Steps**:  
+1. **On-Prem Server**:  
+   ```bash
+   curl -fsSL https://tailscale.com/install.sh | sh
+   tailscale up --advertise-routes=10.0.1.0/24 --accept-routes
+   ```
+2. **AWS EC2 Instance**:  
+   ```bash
+   tailscale up --exit-node=<on-prem-server-ip>
+   ```
+**Validation**:  
+   ```bash
+   # Access on-prem resources from AWS without VPN
+   ping 10.0.1.100
+   ```
+
+#### **Exercise 6: Microsegmentation with Calico**
+**Goal**: Enforce L3-L4 policies across clouds.  
+**Steps**:  
+1. **Deploy Calico on EKS**:  
+   ```bash
+   kubectl apply -f https://docs.projectcalico.org/manifests/calico.yaml
+   ```
+2. **Block cross-namespace traffic**:  
+   ```yaml
+   apiVersion: projectcalico.org/v3
+   kind: NetworkPolicy
+   metadata:
+     name: deny-cross-ns
+   spec:
+     selector: all()
+     types: [Ingress, Egress]
+     ingress:
+     - action: Deny
+       source:
+         namespaceSelector: "!projectcalico.org/name == 'default'"
+   ```
+**Validation**:  
+   ```bash
+   kubectl exec -it pod1 -- curl pod2.default.svc.cluster.local
+   # Should fail
+   ```
+
+---
+
+### **Week 4: Observability & Troubleshooting**
+#### **Exercise 7: Unified Flow Logs**
+**Goal**: Correlate AWS VPC Flow Logs + on-prem NetFlow.  
+**Steps**:  
+1. **AWS Side**:  
+   ```bash
+   aws ec2 create-flow-logs --resource-type VPC --resource-id vpc-123 --traffic-type ALL --log-destination-type s3 --log-destination "arn:aws:s3:::my-flow-logs"
+   ```
+2. **On-Prem Side**:  
+   - Configure **ntopng** or **Elasticsearch** to ingest NetFlow.  
+**Query**:  
+   ```sql
+   -- Find top talkers across environments
+   SELECT src_addr, SUM(bytes) FROM flow_logs GROUP BY src_addr ORDER BY SUM(bytes) DESC;
+   ```
+
+#### **Exercise 8: Break & Fix (Chaos Engineering)**
+**Goal**: Simulate hybrid network failures.  
+**Steps**:  
+1. **Induce BGP Flapping**:  
+   ```bash
+   # On Linux (FRRouting)
+   vtysh -c "configure terminal" -c "router bgp 65001" -c "timers bgp 30 90"
+   ```
+2. **Monitor Impact**:  
+   - Use **CloudWatch Metrics** (AWS) + **Azure Monitor**.  
+**Fix**:  
+   ```bash
+   vtysh -c "configure terminal" -c "router bgp 65001" -c "timers bgp 10 30"
+   ```
+
+---
+
+### **Daily Drills (5-10 mins)**
+1. **`tcpdump` Warmup**:  
+   ```bash
+   sudo tcpdump -i eth0 'icmp' -c 5 -nnvv
+   ```
+2. **BGP Quick Check**:  
+   ```bash
+   vtysh -c "show ip bgp summary"
+   ```
+3. **Cost Hygiene**:  
+   ```bash
+   aws ce get-cost-and-usage --time-period Start=$(date +%Y-%m-01),End=$(date +%Y-%m-%d) --granularity DAILY --metrics "UnblendedCost"
+   ```
+
+---
+
+### **Tools to Keep Sharp**
+| Skill                 | Free Tools to Practice With                  |
+|-----------------------|---------------------------------------------|
+| **BGP**               | FRRouting, Bird                             |
+| **VPN/IPsec**         | StrongSwan, pfSense                         |
+| **Zero Trust**        | Tailscale (free plan), OpenZiti             |
+| **K8s Networking**    | Minikube + Calico                           |
+| **Observability**     | ntopng, Elasticsearch (free tier)           |
+
+---
+
+### **Pro Tips for Muscle Memory**
+- **Repetition**: Do each exercise 3x until commands flow without thinking.  
+- **Break Things**: Intentionally misconfigure BGP/VPNs, then troubleshoot.  
+- **Keep Notes**: Log commands and fixes in a personal GitHub repo.  
+
+**Next-Level Challenge**: Set up a **multi-cloud failover** where traffic shifts from AWS → Azure if latency exceeds 50ms (using **Cloudflare Load Balancer**).  
+
+Want the **step-by-step break/fix guide** for any exercise? I can draft a detailed playbook!
+
+---
+
 To complete your **networking trifecta**, you need a specialization that bridges the gap between traditional infrastructure and cloud-native environments while addressing modern architectural challenges. The **third pillar** should be:  
 
 ### **Hybrid & Multi-Cloud Networking**