Hi there! Thanks for sharing the info.
Just to update my previous year (2017) question about a Debian based distribution that have a web GUI to manage it like pfsense or opnsense to a firewall.
I found the answer to my question. This little software that allow full control of a debian (and others also) based install only using the browser, so no need for a monitor plugged or a GUI to work with the server.
I have not only found, but the news is even better, I found a nice one software to completly manage a Debian server without having an actual GUI installed, and can make it so by Browser.
This one should be included into Debian repos, where can I make such a suggestion? (another question, I know...)
http://www.webmin.com/
"...Webmin is a web-based system configuration tool for Unix-like systems, although recent versions can also be installed and run on Windows.[4] With it, it is possible to configure operating system internals, such as users, disk quotas, services or configuration files, as well as modify and control open source apps, such as the Apache HTTP Server, PHP or MySQL..."
"...Webmin also allows for controlling many machines through a single interface, or seamless login on other webmin hosts on the same subnet or LAN..."
https://en.wikipedia.org/wiki/Webmin
To install on Debian (I added the repository)
http://webmin.com/deb.html