cracauer@
Developer
Thats's why I told you to use a proper install, configured with your user account, to boot the blind server. There is no need to use an installer image. sysinstall can be started from any installed system.
You mean bsdinstall(8)? Hm yes, a minimal basic install where
fbsdinstallfbsdinst and start bsdinstall(8). Sorry I needed so long to catch it ... 
That's not the point. The point is that some innocent newbie might want to install FBSD on his/her headless box. My intention was to provide an install medium that they can download to do that. I can create it, you can create it, but most non-UNIX folk can't do it. They might be interested to give FBSD a try on their NAS box or such, but they can't install it because there is no headless install image they can download.
That's a really nice short poem! I still have hope that FBSD becomes even more welcoming to interested newbies. At least AFAICT there has been a lot of improvement concerning this in the last decade.
I'm with you 99%
...except with this. These folks repair our roofs, drill our teeths, etc. pp. They have every right on earth to have access to good IT stuff. I really think it's a matter of attitude. Why is Linux so omnipresent in consumer hardware? Because some guys understood how to make it accessible for non-IT-nerds. It would benefit FreeBSD if it's easier to access. Then the young kid that learns FBSD now could become a skilled kernel developer in 15-20 years.
All the DHCP servers I've seen on consumer hw let the client choose it's hostname. So then they could easily use the name (freebsd) instead of the IP#.
Making stuff easier for appeal is what had Wayland years-early, systemd, and Docker-reliance everywhere
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If you are talking about updates/upgrades (as opposed to installing for the first time) I am more sympathetic. I have never liked freebsd-update, nor am I thrilled about pkg-izing the base. Updates should be as painless as possible. Ideally no installed apps breaks even when a major update is made.
I was thinking about doing something using the mac address which assumes you have something on the same local network. The ip address might work too, perhaps with the hostname.
Maybe you don't. Set it to a fixed key you already know. I would have your install run sshd out of /tmp so the real system can be set up properly with out all the security holes that might be forgotten later.
* bsdinstall(8) ("SCRIPTING").
Wrong preliminary: I do NOT want to hack up a crippled installer thing. Instead, all I wanted was a version of the official DEFAULT installer with just one difference (which most likely will require more than one configuration knob to be changed, thus it should be tested and thought out thoroughly):
Interesting challenge. Reminds me of copying the DOS Fastlynx program to a target system without using floppies. You had to set the serial port as command input source. The remote program gets a ready signal and transfers itself to the c: current dir on the other side. ..
IIRC the default behaviour is that boot(8) switches the console to serial if no keyboard is found. Thus booting w/o a keyboard should get you where you want? Else you could edit the rc.conf(5) on the install medium to load the appropiate driver, i.e. you must know it's name and add the line
kld_list="${kld_list} serial_driver_here". Unfortunately, the automagic driver loading of FreeBSD is far from beeing perfect, at least in 14.x. But then you have an installation image specifically for that hardware. I'd like to have the topic of this thread beeing s/th like "an installer image to perform a headless install over network via ssh(8)" on ANY hardware, i.e. most, as many as possible. Sorry I forgot that "headless" also includes serial console. Maybe I have to open another thread that includes network and ssh?The whole thing seems kind and of weird to me as the main situations where you're likely to want this are ones when you'd likely have hardware support for a network monitor or the ability to plug one if those cool network Raspberry Pi KVM clients.
No, the environment I had in mind is a SOHO of non-IT-nerds. It would also work in more advanced networks of hobbyists and professionally managed network environments, but these can easily create such thing themself, taylored to their specific needs and likings.
The installer supports full breakout from the shell if you have enough memory but headless is not funny.
OTOH that means 1. it runs on most machines and 2. it's reasonably small.
Yes, this is the mfsBSD way, likely what I prefer too, as it has one huge advantage: it doesn't access any storage except the install medium, because the running OS is on a md(4). And once that is up and if it fits into RAM, you should be able to plug it out, so you can install to a medium pluged into that same hardware interface (are there machines with just one USB port?). 2nd advantage is you can have a password, but that applies to the default installer image as well -- if you want, you can edit the config and set any pw you like.