TDLR:
* The challenge had two stages
* First, bypass the firewall by setting the SNI to public.frontline.cloud.flu.xxx but the HTTP host to secret.frontline.cloud.flu.xxx
* Second, bypass the router via Socket.io request summgle

Detailed writeup:
[https://fh4ntke.medium.com/fluxcloud-frontline-writeup-8e2dbf095d57](https://fh4ntke.medium.com/fluxcloud-frontline-writeup-8e2dbf095d57)

Original writeup (https://fh4ntke.medium.com/fluxcloud-frontline-writeup-8e2dbf095d57).