So, you want to play Killing Floor 1 in 2023 with friends and want to go past the listen server/’host game’ option in the main menu. You want a full-fledged server with custom maps which works and shows up in the server list to fill a couple slots even. This guide isn’t going to majorly handhold the entire server hosting process, but references will be made where needed. Focus is put on operating the KF server on Linux based operating systems, references in particular are made to Debian 12. I’ve also included a couple of recommendations towards client configuration as well.

• Basic SteamCMD instructions/KF Server install.
  
• Basic Setup, WebAdmin, and fixes needed in 2023.
  
• Custom map acquisition, installation, and basic download server setup.
  
• Basic mods/mutator installation and configuration.

• I've not figured out switching between KF and KFO yet. I can't find information on it. You can switch it manually in the WebAdmin UI though.
  
• $ refers to using the shell in Linux as a normal user and # refers to using it as root.
  
• I'm not an expert by any means. I'm showing what I know though as getting to this point has been painful enough.
  
• I've left some notes in for Windows server users. I might be able to help a bit in terms of translating this guide to Windows here and there, ask in the comments if you can't figure something out.
  
• I use generics throughout for config/commands including: "kfuser" for the system user, "kf1server" as the server folder, "10.20.30.40" as the public IP address.
  
• This is my first Steam guide and I don't particularly like the Steam Guide editor hahahaha.

Tripwires Official Guide On Hosting A dedicated Server [wiki.tripwireinteractive.com]
Killing Floor Portable - A set of configuration files and mutators for Killing Floor server. [github.com] I haven't used it directly but It might be worth looking at for an idea of simple mutators and more advanced mutator config.
(Archived 2010) KF-Wiki guide to Dedicated Server hosting. Might be out of date for some current version features.[web.archive.org]
https://cs2bus.com/sharedfiles/filedetails/?id=734724615

To run a Killing Floor server the specifications aren’t particularly stout; It uses only one thread and around 300 megabytes of RAM at most. Low end VPS services or an older computer will be fine. I’m mentioning again this guide is predominately Linux only as most dedicated servers use such operating systems.

The KF server is available on Windows and is largely configured in a similar way but mentions to file paths will be different and some other procedures might have to be changed.

I’ve used Debian 12 for this most recent install without much trouble. Other distributions should be fine if they have support for 32-bit applications. This needs to be enabled for Debian for example and IIRC it does for Arch too. Anything specific to distribution will be done when installing SteamCMD and other guides can be followed for your particular situation.

Port forwarding is also important with the following ports needing to be opened:

• 7707 UDP (Game Port)
  
• 7708 UDP (Query Port)
  
• 7717 UDP (GameSpy Query Port, not sure if it's reused or not)
  
• 28852 TCP and UDP (Allows your Server to Connect to the Master Server Browser)
  
• 8075 TCP (Port set via ListenPort that your WebAdmin will run on)
  
• 20560 UDP (Steam Port)
  
• 10707 UDP (Genuinely no idea but it seems to use it)

On a typical VPS install, ports are usually exposed by default. If you’ve configured a firewall, you’ll need to open them for the mentioned function. If you’re using your home network/internet you need to open these ports on your router. If this isn’t an option (in the case of student accommodations or ISP restrictions) I would strongly recommend just renting a cheap VPS. Otherwise, some VPN providers do provide port forwarding options for this use case but I can’t recommend any.

SteamCMD can be installed from the repos of most distributions. To do this I will direct you to the guide on the Valve Dev Wiki which covers this well. I would also recommend checking your distributions wiki/forums for information. Do take the time to create a separate user for running SteamCMD; it can also be used for running the KF Server but you may want to create a dedicated account if you’re running other game servers. I am going to assume in this guide that you'll being using such a user's home folder to hold game files.

https://developer.valvesoftware.com/wiki/SteamCMD

Next is installing the server… you’d think but you first need to create a Steam account. DO NOT use your current Steam account used for playing KF or other games and create a new one. You DON’T need to buy Killing Floor on this account, you just need to login with it on SteamCMD to download the server. Past this, the account isn’t used again and I’d recommend just leaving it as a bare account with no Steam Guard for simplicity.

So this is the rundown for SteamCMD:

Create a folder in your home folder to contain the KF server.

Set the install directory for Killing Floor

Start SteamCMD and Login with the specific user created for SteamCMD

Steam will most likely also ask for a Steam guard code from the email address used to setup the account. (don't use 10 minute mail!)

Download the server. Note that AppID 215360 is for Linux only. Use AppID 215350 for Windows.

Exit SteamCMD and check the folder for the server files. It should be a variety of folders.

And that’s the KF server software downloaded. Running it is the next stage.

This section will cover a basic server that'll present to the world and run fine in a totally stock configuration. This might be enough for you if you want to just run stock maps.

In the new KF server folder is the ‘System’ folder which contains the executable/binary for running the server as well as map files, the configuration file, and is where mutators/mods can be installed. To start with, create a file to be used as a shell script to launch the server for the first time.


Copy this script into it for a basic initial setup:


Alternatively, screen can be used to better manage the process and is what I would recommend doing. The following configuration names the screen instance, limits it 1024 lines output and detaches it automatically. (you may need to install screen first depending on distro)


Run it.


The server at this point will fill your terminal with it’s start up messages and quickly move to broadcasting the games status.

Screen users will not see this and can run:
To check if there’s a running detacted terminal. Then they can run:
To reattach the process and see output and to...

Stop the server by using a SIGINT with CTRL+C. (As far as I know this is the most graceful shutdown you’re getting. This is a sign of things to come…)

Before going any further however, an important fix is best made now. The downloaded KF server has outdated Steam libraries that don’t work at all which causes server information and the server listing not to show up in game. Fixing this is simple. Big thanks to Steam user NonstopKarnage for posting their fix for this.

The three Steam library files that come with the server install are going to be backed up by being renamed and they’re going to be replaced by a symbolic link to the same files from the SteamCMD install.
From the SteamCMD install directory. On my Debian 12 Setup it’s defaulted to:
~/.local/share/Steam/steamcmd/linux32/
(~ refers to the home directory of the current user, please change accordingly to your setup)
All the commands to do this are as followed:
Setting the LD_LIBRARY_PATH to this location is also recommended and can be done with the script to start the server. I have included it in both the scripts provided so far.

The server should have at this point generated KillingFloor.ini which is the main configuration file for the server. We’re going to edit this using nano (or whatever you like) to mainly enable WebAdmin for simpler configuration. Configuration of server name, game password and more can be done manually here but it can be a chore as the configuration file is formatted in a dreadful way. Also, I believe it’s the intended way for nearly all base configuration to be done.

Enabling WebAdmin:
For your own sanity use the find/’Where is’ option in your editor of choice. In nano this is activated using CTRL+W. Search for the title of the sections, this search is case sensitive.

Search for section [UWeb.WebServer] by searching just “UWeb.WebServer”. Set “bEnabled=True” to enable the web server. You can also set the port of the web server by using setting “ListenPort=8075” where 8075 is default and can be changed to whatever you want. Keep note of this to access the server later.

Admin Name:
Doesn’t really matter. Just go with something you can remember.
Search for section [Engine.GameReplicationInfo] and set “AdminName=YOURNAME”.

Admin Password:
Does matter a bit. You connect over unsecured HTTP so please do use a unique password that doesn’t mean anything anywhere else.
Search for section [Engine.AccessControl] and set “AdminPassword=YOURPASSWORD”.

At this point you can run the server again and connect to the web server on the IP address of the server. On a VPS this should be available in dashboard or be the same IP used to connect to the server.

If you’re using a home network or configuring it on the same local network, you might be best using the local/LAN IP address (found via ifconfig) to access the server or you can see your own public/external IP address on whatismyipaddress.com

Type http://10.20.30.40:8075/ where 10.20.30.40 is replaced your servers IP. You’ll be asked for a username/password. Enter the values that you’ve just configured and you’re in!

• Yes it’s a product of the time and designed for low resolution monitors, do zoom in. Second it has two sections of ‘current’ and ‘defaults’.
  
• Current shows a player listing, a more advanced player listing for banning/kicking, direct access to the server console and the list of mutators.
  
• Defaults contains all the other options to do with the server such as name, game password, map lists, chat enable/disable, map voting options, kick voting options, sandbox options, game length/difficulty, list of banned players and another voting config.
  
• Most of these are self-explanatory and I would recommend setting a server name and the following options for map voting as well as setting game length to Long (for 10 waves).
  
• The Maps tab are where the map lists are configured. By default only the 5 launch(?) maps are listed and playable on the server. Maps listed on the left are installed but not listed and maps on the right are listed and therefore playable. Click the “>>” to move all the maps across and then manually select “KF-Menu” and move it back to the left with “<”. (KF-Menu is the menu screen in the client game, it’s not playable. It won’t crash the server or anything but yeah.)
  
• Setting a game password here might be of interest if you want to keep the server private.
  
• Restart Level/Map are both present on both sections of the WebAdmin interface and both do the same thing. The map is restarted and this acts as a ‘Warm Restart’ of the server. Changes made in the WebAdmin UI will apply after a map restart or natural map change, even including mutators. This is the quickest way to change difficulty for example.

At this stage you have a server that’s listed in the server browser and can be used to play all official maps with friends and anyone else who wants to join.

I ran out of space on Step 2!

Anyways here's a simple configuration for a systemd unit/service so that the server can be started along with the system (enabled) and managed otherwise with systemctl.
Utilising this may depend on distribution of Linux. Check your respective distro's wiki for information.
Link to guide for managing creating and enabling systemd services in Debian [wiki.debian.org]

You can also replace the "ExecStart=" value with the location of your script file. This is up to preference but due to MutLoader, I don't find much reason to change the start command .

Okay, lets say you want to play something more homebrewed on the server. This is a long winded but simple process with a couple of steps that might cause irritation so be ready.

Getting maps is the first problem and step. One major bug rules this area and is a trap for many as the Steam Workshop is and has been the main place for custom maps and mods/mutators/fixes to be uploaded.

However, Killing Floor won’t download Workshop items if you have more than 50 subscribed workshop items in any/all games on Steam. Not just KF, ALL games that use the Steam Workshop. So, if you were like me and had like 200 GMOD addons from 10 years ago on your account, you won’t ever get workshop maps downloaded. You might get a freak download here and there but that’s after restarting the game a lot of times and just waiting for chance.
Now you have a couple choices here:

• Unsubscribe from all Steam Workshop items across all games to use Workshop. (Steam has a button dedicated to this).
  
• Find maps outside of the Workshop on sites like Gamebanana, ModDB or even the rare listed open directory download server.
  
• Skim through this archive I made which contains a massive number of maps for Killing Floor which were hosted on the download servers I can find. (Work In Progress)

Regardless of which you choose, clients need the map files first. Killing Floor is best used with a download server, a process I will go over after map acquisition.

Please see my archive.org upload of 700+ dependency free maps just below this paragraph.These are in a big 7z file in the .rom format. Not all of these will work but you can put them in the maps folder on your client/game and see what you like!

https://archive.org/details/Killing-Floor-2009-Custom-Maps

The Workshop has the biggest collection of custom content for Killing Floor and is usually the most up to date as well. Supporting files for maps such as extra code, textures and sounds are included and you might have the listing of files used even in the description.

I would recommend making a collection or faving your disgusting GMOD addons (don’t lie, I know what you people do on gm_bigcity) or other workshop items and pressing the ‘big unsubscribe all button’. Restart Steam before trying to download KF workshop content after doing the big unsubscribe. If you finish up with downloading from KF’s workshop, you can then easily resubscribe.

After all that and you add a map from the workshop, you’ll get a notification in the top right corner in plain white text letting you know the map is downloaded/downloading. If you don’t see this, click on the Multiplayer tab, and go back to the main menu, this starts the download in most cases. You can check when selecting a map for solo play if it has loaded.

Navigate to your games installation directory and the downloaded map will be in the ‘Maps’ folder as a .rom file. If it requires any additional files, their locations in the Sound/Texture/System folders should be mentioned in the items description most of the time. Otherwise, you can quickly check manually by looking at the modified dates of the folders and seeing if new contents have been loaded into them.

On the server side, you’ll want to put the .rom files into the ‘Maps’ folder. (I like using WinSCP for this task) Any additional content will go into the same folders as they were on your client install. I advise you to also copy all these files as well to a separate folder/directory at this time to start the basis of the download server. All of them in one folder, no separation needed.

The 1KB .ucl file in the System directory named the same as the .rom map file can be ignored as this will be generated by the server.

It’s perfectly possible that every player could download the map from the workshop and then join the server. This would require coordination within your friend group and would pretty much exclude anyone joining publicly. (Keep in mind, you’d need to tell all your friends to nuke their workshop subscribed items as well). You could even go a bit old school and even just send the map files around to each player.

Ultimately the best option here is to setup a download server for connecting players to download the current custom map to their computer. Killing Floor supports this best by using a basic HTTP server/web server as a source for map downloads. You don’t need a fancy domain or website for this to be clear. This is also separate from the web server used to host the WebAdmin UI.

For this, I recommend using Apache2. You can use the latest version available in your distribution. The goal is to setup a web server and the map files are best placed on the ‘root’ of the web server as defined in its configuration. I will cover this for Debian and Apache2 briefly below but you should be able to follow any guide for your distribution to setup a basic web server/website and then you can just place map files at the root of the web server’s directory.

Apache2 on Debian already comes preconfigured to display a default webpage on port 80. It uses the directory /var/www/html/ as it’s root directory for the website. Map files can be copied or symlink-ed (using "ln -s") to this directory, keeping the case the same as the map file in the “Maps” directory.

I would recommend replacing the default ‘index.html’ with a blank “index.html” file (easily created by doing “touch /var/www/html/index.html”) to make it not list the contents of the directory.

Then in KillingFloor.ini under section [IpDrv.TcpNetDriver] you need to set the following options:
Under section [IpDrv.HTTPDownload] set “RedirectToURL=http://10.20.30.40:80/” where 10.20.30.40 is your IP (and desired port if set on the webserver to not be at port 80. You will also need to set "UseCompression=False" from being 'True' if you're using .rom files instead of compressed .uz2 (.rom.uz2) files.

Fully cold restart the KF server after doing this and to test you can have a friend join or unsubscribe from the custom map on the workshop and delete its files from your client’s “System” directory. The map at this point should download rapidly to the client and load in like normal.

• Map compression is a thing that has mainly gone away with the workshop. I don’t use it for no reason other than I can't be bothered to compress each map. If you find maps online that are compressed (uz2 file format) you can decompress them and use them using the ucc-bin server binary. You can get this in the Killing Floor SDK as well but make sure it's installed in a different place to your normal Killing Floor install.
  
• Make sure that map names are the same in terms of case.
  
• You can do a soft symbolic link instead of copying map files if you wish by using “ln -s” to save on disk space on the server. In my mind, it keeps things simpler too.
  
• You can use a domain name in the RedirectToURL field for the download server without issue but still do include the port. This is useful as you can setup DynDNS with a free domain if you have a dynamic external IP address on the server; as would be the case with most home Internet setups.
  
• Maps may try to download without this but I don’t think its intended by any means. Just setup the HTTP server or instruct every player you want on the server to copy the correct files to the correct places.

Mods and mutators are the same thing as far as I know. Yes, the wording confused me for too long but I’m here to fix that.

My goal for my KF Server is to have a “Vanillia+” experience where some bug fixes or QoL mods are in place but otherwise no big changes are made to gameplay, economy, weapon selection, and perk progression. Therefore, I don't have deep experience with mutators but here's something to get you started with the more basic ones.

https://cs2bus.com/sharedfiles/filedetails/?id=971828546
Follow this Steam guide to uncap the FPS from 85 to 144 or higher. Might as well while you're messing around with this stuff. Needs configuration on both server and client!

MutLoader is a mutator that loads other mutators and does a couple of other tasks. Rather than having a exhaustive server startup script/service you can set them all up with MutLoader to have them load automatically on the server.

MutLoader can be downloaded through the workshop with its files copied to the 'System' directory on your Killing Floor Server install. You need to then edit the server launch options to include MutLoader. So add:

To make the base command like this:

To load a mutator using MutLoader you need its class name. This can be found in the Workshop description most times but can also be found by opening the mod's .ucl file with a text editor. You want to use value from ClassName as shown below.






This MutLoader Configuration would load the CountryTags mutator on each difficulty and would change the server name accordingly to match the difficulty. If you add a new mutator, it must be added to each difficulty as well. To add another mutator just make another line starting with "Mutator=YourMutator.ClassName"

MutLoaderV2.ini:

You can check which mods have been loaded under the mutator page in the WebAdmin UI. You will need to fully reload the server for MutLoader to load new mods on it's start up. (IMO, this would be good practice regardless).

Lastly, for some mods (excluding MutLoader) you'll want to drop them on the download server so it can be served to clients. For purely server side mods, this isn't necessary but for some such as the damage number mod, you'll want to have these client side to work. This is where you would put other non-map custom content too. Just copy all files to the same place where the map files are!

Many mutators exist for many different reasons. From bug fixes to completely changing the game. I recommend the following ones from this collection for my mentioned "Vanilla+" goal:
https://cs2bus.com/sharedfiles/filedetails/?id=3053950873

This project for a 'portable' Killing Floor install also features a number of QoL fixes and other mods that might be worth pinching from:
https://github.com/Vel-San/killing-floor-portable

I hope this guide has help someone somewhere not pull their hair out at this overly complicated process where a lot of information is either lost to time or hard to research as KF2 stuff gets pulled in on searches.

Have fun killing floors!