NAT Flow Simulator
Updated Mar 6, 2026
See how packets are translated as they pass through different NAT configurations — Static NAT, Dynamic NAT, and PAT (overload). Watch the translation table build in real time as packets flow between inside and outside networks.
A hands-on way to understand why certain applications break behind NAT and how port address translation lets hundreds of devices share a single public IP.
One-to-one fixed mapping between a private IP and a public IP.
Press Play or Step to begin the simulation.
NAT Translation Table
Step Log
- Step 1: Host A (192.168.1.10) initiates a connection to 198.51.100.25.— Outbound packet reaches the NAT router.
- Step 2: NAT router translates source 192.168.1.10 → 203.0.113.10 (static mapping).— Source IP rewritten to public address.
- Step 3: Outside server 198.51.100.25 receives the packet from 203.0.113.10.— Server sees the public IP, not the private one.
- Step 4: Server replies to 203.0.113.10.— Reply travels back toward the NAT router.
- Step 5: NAT router translates destination 203.0.113.10 → 192.168.1.10.— Destination IP rewritten back to private address.
- Step 6: Host A receives the reply. Static NAT flow complete.— Round trip complete — mapping stays permanently.
What You're Seeing
Static NAT creates a permanent one-to-one mapping between a private IP and a public IP. Every packet from the inside host always leaves with the same public address. This is commonly used when an internal server needs to be reachable from the internet on a fixed address.
| NAT Type | Mapping | Use Case |
|---|---|---|
| Static | 1 private : 1 public (permanent) | Servers needing a fixed public IP |
| Dynamic | 1 private : 1 pool IP (temporary) | Outbound access with a small pool |
| PAT / Overload | Many private : 1 public (port-based) | Home/office internet sharing |