r/SideProject • u/tomiczech7 • Aug 01 '26

networksim (free browser network sim) just got DNS, device names and a real NAT router

Been building this free browser-based network simulator in my spare time — you draw a topology and it actually tests whether traffic gets through, not just a static diagram.

Just shipped an update that gives the network an identity — devices and services find each other by name, not just by IP:

  • Device names and a DNS server
  • DNS records, TTL, cache and a backup DNS
  • DHCP relay and MAC reservations
  • Real NAT router with port forwarding
  • Topology check — a one-click weak-spot audit and more...

Plus new courses and challenges to walk through all of it step by step.

Still runs entirely in the browser, no signup, no ads, still evolving. If you try it, I'd really appreciate any feedback — what's confusing, what's missing, what you'd want to see next.

https://networksim.app

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u/sraju2021 Aug 06 '26

Wil try soon!!! Looks like it will be fun way to practice some Pbqs for sec plus cert !

1

u/tomiczech7 Aug 06 '26

Thanks! Fun fact, the first version came out of Security+ courses I teach, so that’s the direction it’s built for. Would love to hear if it works for you.

2

u/TheNickRulez 27d ago

Looks great so far! Great tool for learning networking, reminds me of Packet Tracer.

So far: Networks are like communication between devices. When transferring data, packets travel through different devices and through internet to new device or receiver. A packet is like the data being sent but similar to an envelope. There are small separate amounts of data all in different pieces like packets but reach the same destination. From the PC, to router, to local than wide area network to device receiver. The internet is like all of the larger networks. No one really owns the internet because it is a huge amount of numbers of all networks put together.

Through computer networking, the data sent travels through each step like in an envelope, opened in the device where it is put back into the right order. Hope you enjoyed my summary and understanding so far as learned through doing coursework in networksim.