"Who Is There" or "WIT" is a linux app using iptables and ipset to cover your precious services. In fact it's a "Port knocking" server. It waits for your knock and if it recognize you, it will let you in!
Useage:
wit [optiosn]
options:
-h,--help
-version
-a,--auto-cert
-b,--bind-address bind_address
-H,--host-name host_name
-l,--list-name ListName
-P,--policy redirect or drop
-c,--cert-path CertPath
-p,--http-port http_port
-tp,--tls-port https_port
-cp,--covering-ports CoveringPorts
-psk PresharedKey
It creates an ipset list (default name :"WhiteList") and adds iptables rules for each given CoveringPorts. So it redirects all traffic to wit! Then you can authenticate by a HTTP_GET request like below and boom! You can reach your service for 6 hours :)
https://YOUR_BIND_IP/login/?pks=YOUR_PRESHARED_KEY
If you do not set any psk user will be authenticated by any key.