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About

Blog Topic Introduction
This blog covers in-depth information and practical know-how on cloud technologies overall, including AWS (Amazon Web Services) cloud architecture, infrastructure management, cloud security, and cost optimization. It provides useful guides and tutorials suitable for everyone from beginners to experts.

Who Runs the Blog
It is operated by "Cloud Worker," an active cloud engineer with a passion for cloud technology.

Why This Blog Was Created
I started this blog to document various troubleshooting experiences and architecture design know-how gained in the field, and to provide practical help to those who want to learn cloud technologies. It also serves as a personal record to continuously learn and keep up with new AWS services and rapidly changing trends.

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EC2 No Internet Access in Custom VPC: Fix Internet Gateway and Route Table

EC2 no internet access in a custom VPC is one of the most common launch-day failures — the instance is running, but outbound connectivity is completely silent. TL;DR: EC2 No Internet Access — Fix Checklist Step What to Do Why It Matters Complexity 1 Create and attach an Internet Gateway to the VPC Without an IGW, the VPC has no path to the public internet Low 2 Add a default route (0.0.0.0/0) pointing to the IGW in the subnet's route table The IGW exists but traffic has no route to reach it Low 3 Assign a public IP or Elastic IP to the instance Private IPs are not routable on the public internet Low 4 Verify Security Group allows outbound traffic A restrictive outbound rule silently drops all egress Low 5 Verify Network ...
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EC2 SSH Connection Timeout: Which Security Group Rules to Check

An EC2 SSH connection timeout is one of the most common blockers when launching a new instance — the fix is almost always a missing or misconfigured inbound rule in your Security Group. TL;DR — Diagnostic Steps at a Glance Step What to Check Common Fix 1 Security Group inbound rules Add SSH (TCP 22) from your IP 2 Subnet route table Ensure 0.0.0.0/0 routes to an Internet Gateway 3 Network ACL rules Allow inbound TCP 22 and ephemeral return ports 4 Instance public IP / Elastic IP Confirm a public IP is assigned 5 Key pair and SSH username Use correct private key and AMI-specific username Why SSH Times Out Instead of Refusing A connection refused error means the TCP handshake reached the host but nothing is listening. A connection timed out error means packets never arrived — or replies never returned. On EC2, that silence is almost always a network-layer block, not an OS-level problem. The Se...
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Difference Between IAM User and IAM Role: Which One Should Your EC2 Use?

Understanding the difference between IAM User and IAM Role is critical — choosing wrong means either hardcoded credentials in your app or a silent security exposure you won't catch until an audit. TL;DR: IAM User vs IAM Role at a Glance Dimension IAM User IAM Role Identity type Permanent, named human or service identity Assumable identity with temporary credentials Credential type Long-lived access keys or password Short-lived STS tokens (auto-rotated) Attached to EC2? No native attachment — keys must be embedded Yes — via Instance Profile, injected automatically Rotation required? Manual — your responsibility Automatic — AWS STS handles it Recommended for EC2 → S3? No Yes — always Cross-account access Requires separate user per account Native — assume role across accounts Audit trail Tied to user identity Tied to role + session name in CloudTrail What IAM User and IAM Role Actual...
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