It completely prevents connecting with a second client (normal or HC) to a dedicated server even if kickduplicate is disabled.

Makes MP testing with two clients on a local machine impossible now.

Irony as forceheadlessclient=1 made it into Dev the same time this did (http://feedback.arma3.com/view.php?id=4662).

*EDIT by Dwarden*
Dwarden has suggested buying another copy should be necessary for HC w/o compromising security layers.

You can use SteamCMD to run multiple times per machine,
as long as you use login to STEAM account which owns arma 3 alpha
each new SteamCMD session of course needs new unique account (with arma 3 ownership)

rest is unrelated ...

My original (apparently unrelated) note stated:
/*

1. Add a switch to the dedi server binary -client or create a new dedicated client that is cdkeyless or universal (as the dedi server operates in this fashion)

2. Only allow the HC/Dedicated client to connect to localhost (127.0.0.1) to nullify security issues.

As issues exist with remote HC (https://dev-heaven.net/issues/62500) limiting HC to localhost only shouldn't have a negative impact.

Sure, the admin may hack their own server via this method using an "unbannable client" but such easier ways as proving grounds locked to UID exist already.
*/

The main concern for a HC would appear to be a security issue.

here's my viewpoint on that

Either utilise a -HC switch parameter on a dedicated server binary
or create a HC.exe
For either option, do not allow any user input

Possibly
Only allow 1 instance of a HC on 1 server at any time. (If they all have the same USER ID, this checking system already exists)
If multiple HC's are allowed , use a HC password for the server

In the server config have some or all of the following optional settings

Define if HC is allowed
Define HC IP address, if not defined, by default it whitelists the server IP
Define a HC password (Would seem a very easy solution to clients trying to cheat)

As an overview, this should prevent any clients abusing a HC for malicious acts

From the perspective of a server admin (with backend access) cheating, its not even worth considering as there are much easier ways to influence the gameplay without going to the extent of installing a HC

Having the ability to kick a HC may be a worthy condideration for additional scenarios other than a cheating one.

So why not
Define all HC's with the same UserID (if using the rule "Only 1 HC allowed per server" why not?) or have an incremental USE ID for the HC;'s via #userlist
Add an admin command #KickHC

dedicated Slave server in relation to Master dedicated server
is definitely one of things on my MP ideas list, but
there might be obstacles, e.g. how Master recognize the Slave portion as client

commandline
Arma3server.exe -slave -masterIP=<IPv4> -masterPort=<number>

As long as BI has no native solution for better (multithreaded?) script processing, it should be possible to use this HC (dedicated client) as a workaround.
(I know the Arma 2 engine a bit. A few months ago, i tried to reduce the login-time on full, long running dayz servers :/ )

I think it would be fair to make use of HC possible, without paying for one or more extra licences.

So how do people who make MP stuff test now ?

I personally use up to three clients (two normal clients plus HC) beside a dedicated server on my local machine to test MP stuff, but, as already written above, it's no longer possible.

it still possible,
You just need new STEAM account which owns Arma 3 Alpha
next to one running Arma 3 dedicated server
and you can use STEAMcmd for that https://developer.valvesoftware.com/wiki/SteamCMD

@Dwarden
Makes absolutely no sense. No one will buy 2 or 3 A3 copies just to test MP content he/she provides for free or invest time into steamcmd whatever just to do a quick test of a change.

I have created a whitepaper of sorts that goes beyond the issues currently plaguing HC that could solve the issue of AI performance within the core game engine. It has fancy graphics and doesn't drone on and on. Most importantly it offers a solution that should be accepted by both parties as it resolves all concerns.

https://www.dropbox.com/s/y5ourdvidcxw6zf/Arma3ServerWorldspaces.pdf

@zorrobyte, a better HC implementation won't fix the main problem of the engine. That is, the engine simulates itself to death. If a rice bag falls over 200 miles away from the clients the server will send an update to each client and it will be simulated on each client even if the clients will never see or get near the rice bag.

More objects = more simlations = less FPS. A HC does just offload AI from the server to another instance leaving the server a little bit more room to breathe but does not solve the heart of the problem.

(At least that was afaik the way it worked in A2/OA but I doubt that it has changed seeing that there is a script module in A3 which disabled the simulation of objects more than 2000m away from the player and hide them with hideobject. Please correct me if I'm wrong).

Anyway, still doesn't change the fact that you now need to buy more A3 copies just to do something simple as MP testing.

@Xeno
Point taken. That has been an issue for the longest time (https://dev-heaven.net/issues/6963).

Although with A2 BIS has made the final statement on the issue (https://dev-heaven.net/issues/6963#note-28) maybe things will change for A3.

I feel as if such dialog were to be opened again, a separate ticket would need to be created as this ticket focuses on a stop-gap or addition to your solution.

0.54 change log reported the forceheadlessclient issue as closed

"0004662: [Engine] Server does not assign player a slot where forceHeadlessClient=1; - closed."

Is this closed for the issue listed here or will it be implemented at a later state ?

Testing this morning and it is not resolved - as per 0004662 slot can be reserved by manual edit of Mission.sqm, but no HC is forced into that slot, nor can any player be moved to that slot.

Still doesnt work as of v.0.72 stabile branch.

Are there any plans for making this work in the future?
It cant be true we will be forced to buy 2 copies of the game, just to do some testing with HC tbh.

I believe the ideal solution would be to have a HC.exe, which you can run 1 instance of on each steam account, similar to the current arma3.exe setup, but dedicated HC executable.
Dunno if its to difficult to implement though, but something has to be done.

Link updated for AI pref suggestions in general and native HC Fix:
https://drive.google.com/file/d/0B3VdHnk7BX1BUGtMRmMyRDRza1U/edit?usp=sharing

Still waiting for the HC DLC (Would be good solution)

Not an issue anymore. Should be closed.