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  "path": "/nagesh_k_2003/the-beginners-guide-to-private-vs-public-ips-ex-banking-systems-3848",
  "publishedAt": "2026-06-24T11:33:43.000Z",
  "site": "https://dev.to",
  "tags": [
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    "cloud",
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  "textContent": "When I first studied IP addresses, I thought:\n_“Private IPs are only inside my router, and public IPs are only for the router itself.”_\n\nBut that’s not the full story. In real production systems — like a banking website — both public and private IPs exist together. Each has a specific role, and understanding this is the key to mastering AWS networking.\n\n##  🌍 Why Not Make Everything Public?\n\n**Imagine a bank has three servers:**\nWebsite Server\nApplication Server\nDatabase Server\n\n**Option 1:** Give all three **public IPs**.\nTechnically possible, but very dangerous.\n\nWhy? Because attackers could directly connect to the database server from anywhere on the internet. That’s exposing the vault to the street.\n\n##  ✅ Better Design: Public + Private Together\n\nHere’s the safer architecture:\nCustomer\n↓\nInternet\n↓\nWebsite Server (Public IP)\n↓\nApplication Server (Private IP)\n↓\nDatabase Server (Private IP)\n\n##  🪜 Step‑Wise Banking Example\n\n**Step 1:** Customer Opens Website\n**You type : **mybank.com\n**Your browser reaches the Web Server at:** Public IP = 13.233.10.100\nThis must be public because customers worldwide need access.\n\n##  Step 2: Login Request\n\nYou enter username + password.\nThe request hits the Web Server (Public IP).\n\n##  Step 3: Web Server Needs Data\n\n**The web server doesn’t store balances. It calls the Application Server:** Private IP = 10.0.2.10\nThis server is inside the bank’s private network.\n\n##  Step 4: Application Server Queries Database\n\n**The app server asks the Database:** Private IP = 10.0.3.20\n**Database returns:** Balance = ₹50,000\n\n##  Step 5: Response Flow\n\n`Database → App Server → Web Server → Customer Browser.`\n**You see:** Welcome Nagesh , Balance: ₹50,000\n\n##  🔒 Why Use Private IP for Database?\n\n**Because the database contains:**\nPasswords\nBalances\nTransactions\nCustomer data\n\nWe don’t want random internet users scanning or attacking it.\nWith a private IP, the database is invisible from outside.\n\n##  👨‍💻 How Do Bank Employees Access Private Systems?\n\nThis is the part most beginners get confused about. Employees don’t “log in” directly to a private IP from their laptops. Instead:\n\n**Method 1: Inside Bank Network**\nEmployee PCs are already inside the private LAN. Their devices get private IPs (like 10.1.1.50) and can reach the database (10.0.3.20) internally.\n\n**Method 2: VPN (Very Common)**\nEmployees working remotely connect via a VPN tunnel.\nTheir laptop joins the bank’s private network virtually.\nNow they can reach private servers safely.\n\n**Method 3: Bastion Host (AWS)**\nIn cloud setups, employees first connect to a bastion host (a secure jump server with a public IP). From there, they can access private servers inside the VPC.\n\n##  🎯 The Most Important Rule\n\nPrivate IP ≠ Nobody can access it.\nPrivate IP = Cannot be directly reached from the public internet.\n\n**Access is possible only if:**\nYou’re inside the private network, or You connect through VPN, bastion host, or secure tunnels.\n\n##  ☁️ AWS Translation\n\nBanking Architecture → AWS Setup:\nInternet\n↓\nLoad Balancer (Public IP)\n↓\nEC2 Web Server (Public IP)\n↓\nEC2 App Server (Private IP)\n↓\nRDS Database (Private IP)\n\n##  🚀 Final Reflection\n\nAt first, I thought public vs private IPs were just about routers and home devices. But now I see:\nPublic IPs are for systems that must be reachable from the internet.\nPrivate IPs are for internal systems that should only communicate within trusted networks.\nThis banking example makes it crystal clear — and it’s the same principle AWS VPCs, subnets, NAT gateways, and security groups are built on.",
  "title": "The Beginner’s Guide to Private vs Public IPs, Ex - Banking Systems"
}