SteamCMD Server Setup

Intermediate40-60 minutesWindowsUnturned ServerNotepad++

SteamCMD is a command-line version of the Steam client that allows server operators to install and update dedicated server software without a graphical interface. When hosting multiple Unturned™ servers on the same machine, SteamCMD is required because the Steam Library installation method does not support running multiple instances simultaneously.

57 Studios™ has documented the complete SteamCMD server setup workflow based on the official SDG documentation. This article covers SteamCMD installation on Windows and Linux, server download via app_update 1110390, batch script creation for server launch, automation through update scripts, and common SteamCMD errors.

Documentation source: This article references the official Smartly Dressed Games modding documentation Chapter 118 (Using SteamCMD Advanced Setup).

Who this article is for

This article is written for server operators who need to host multiple Unturned™ servers, operators who prefer command-line tools over graphical installation, and anyone setting up automated server deployment.

SteamCMD installation

Windows installation

1. Download SteamCMD for Windows from the official Valve website.
2. Extract the contents of the zip file to a directory (e.g., C:\steamcmd\).
3. Run steamcmd.exe.

Linux installation

Installation on Linux varies by distribution. Refer to Valve's Linux documentation for distribution-specific instructions. Once downloaded, run the steamcmd.sh script.

Installing the Unturned Dedicated Server

After launching SteamCMD, run the following commands:

login anonymous
app_update 1110390
quit

The app_update 1110390 command downloads the Unturned Dedicated Server application. The same command can be used to update an existing installation. Append the validate flag to verify file integrity and repair missing or corrupted files:

app_update 1110390 validate

After the download completes, the server files are located at .../steamapps/common/U3DS/ relative to the SteamCMD directory.

Launching a server on Windows

Create a batch file (.bat) in the U3DS directory to launch a server.

Internet server batch file

start "" "%~dp0ServerHelper.bat" +InternetServer/MyServer

LAN server batch file

start "" "%~dp0ServerHelper.bat" +LanServer/MyServer

Replace MyServer with your chosen ServerID. The server's save data and configuration files will be in a folder named after the ServerID within the Servers/ directory.

Launching a server on Linux

Run the appropriate command in the terminal from the U3DS directory.

Internet server

./ServerHelper.sh +InternetServer/MyServer

LAN server

./ServerHelper.sh +LanServer/MyServer

Post-installation configuration

After the first launch, the server generates its configuration files. Use the Shutdown command to safely close the server, then edit the configuration files in the Servers/<ServerID>/ directory.

For Internet servers, configure:

• Game Server Login Token (GSLT)
• Fake IP or Port Forwarding

Automation and updates

SteamCMD can be scripted for automated updates. Create a text file with the SteamCMD commands and pass it as an argument:

// update_script.txt
login anonymous
app_update 1110390 validate
quit

Run with: steamcmd +runscript update_script.txt

Diagnostic table

Symptom	Most likely cause	Resolution
app_update fails	Internet connection issue or Steam outage	Check network connectivity; try again later
Server files not found	Wrong working directory	Verify you are running from the correct U3DS path
Batch file does not launch	File extension is .txt instead of .bat	Enable file name extensions in Windows and rename
"Access denied" error	Permissions issue on Linux	Use chmod +x on the shell script
Server starts but crashes immediately	Corrupted configuration files	Delete the ServerID folder and regenerate
validate finds errors	Corrupted server files	Run app_update 1110390 validate again
Multiple servers conflict	Same ports configured	Use different Port values in each server's config
SteamCMD login fails	Network proxy or firewall	Configure SteamCMD proxy settings

Best practices

• Use SteamCMD for all production server installations.
• Create a separate batch/shell script for each server instance.
• Use the validate flag in automated update scripts.
• Keep SteamCMD and the server software updated.
• Document the server's ServerID and port configuration.
• Test the server startup sequence before deploying to production.
• Use descriptive batch file names that identify each server instance.

Frequently asked questions

Why use SteamCMD instead of the Steam Library installer?

The Steam Library installer only supports a single instance of the Unturned Dedicated Server on one machine. SteamCMD allows multiple independent installations, which is necessary for hosting multiple servers.

Can I run a server without SteamCMD?

Yes. The simple setup described in the Setting Up an Unturned Server article uses the Steam Library installer. SteamCMD is only required for multi-server setups.

What does the validate flag do?

The validate flag checks the integrity of all downloaded files against their expected checksums. Missing or corrupted files are re-downloaded. This is useful for repairing a damaged server installation.

How do I update the server software?

Run app_update 1110390 again. SteamCMD downloads only the changed files. The server configuration files are preserved across updates.

Can I use SteamCMD on a headless Linux server?

Yes. SteamCMD is designed for headless server operation. The steamcmd.sh script runs in a terminal without requiring a graphical environment.

Appendix A: Example batch files

Windows Internet server

@echo off
start "" "%~dp0ServerHelper.bat" +InternetServer/MyServer

Windows LAN server

@echo off
start "" "%~dp0ServerHelper.bat" +LanServer/MyServer

Appendix B: External references

• Smartly Dressed Games official modding documentation - the official SteamCMD guide.
• Valve SteamCMD documentation - official SteamCMD reference.
• Setting Up an Unturned Server - the previous article.
• Server Hosting Rules - the next article.

Authoring checklist

• [ ] SteamCMD installed (Windows or Linux)
• [ ] app_update 1110390 completed successfully
• [ ] Batch/shell script created for each server instance
• [ ] Server launches without errors
• [ ] Configuration files generated after first launch
• [ ] GSLT configured (for Internet servers)
• [ ] Update automation script created

Integration with other systems

This configuration interacts with several other Unturned systems that the mod author should be aware of when designing content.

Interaction with the asset definition system

Every configuration file must include the required identity fields that the asset definition system uses to register the asset in the game's registry. Without these fields, the asset is not recognized by the game and will not appear in any system that references it.

Interaction with the localization system

Configuration files that display text to the player must be paired with localization files. The English.dat file provides the default language display values. Additional language files can be added for multilingual support.

Interaction with the master bundle system

Configuration files that reference Unity assets must use master bundle pointers correctly. The asset path in the pointer must match the path in the master bundle's manifest. A mismatch causes the asset to fail to load without crashing the game.

Interaction with the validation system

The game validates configuration files during the loading phase. Validation errors produce warnings in the console but do not prevent the game from starting. The affected asset may use default values for invalid fields.

Performance considerations

Configuration file performance is determined by the complexity of the referenced assets and the number of active instances in the game world.

Memory footprint

Each loaded asset occupies memory proportional to its data size. Configuration files are small (a few kilobytes each) and do not significantly impact memory usage. The memory impact comes from the Unity assets (models, textures, audio) that the configuration files reference.

Loading time

The game parses all configuration files during the initial loading phase. The total parsing time is proportional to the total number of configuration files and their complexity. For most mods, this overhead is negligible (milliseconds to low seconds).

Runtime performance

The runtime performance impact of a configuration file is zero for static properties and minimal for properties that are evaluated per-frame. Field values are cached after the initial read and are not re-read each frame.

Testing and validation

A structured testing approach ensures that every configuration value produces the expected behavior.

Unit testing

Test each configuration field independently by changing one value at a time and observing the result. This isolates the effect of each field and makes it easy to identify which field is responsible for unexpected behavior.

Integration testing

Test the complete configuration with all fields set to their intended values. Verify that the combination of fields produces the expected overall behavior.

Regression testing

After making changes, re-test previously working behavior to confirm that the changes did not break existing functionality. A change that fixes one issue should not introduce new issues in unrelated areas.

Stress testing

Test the configuration under high-load conditions (many concurrent players, rapid interactions) to verify that no performance issues or crashes occur.

Common authoring mistakes

Mistake 1: Missing identity fields

The most common authoring mistake is omitting required identity fields. Without a GUID, Type, and ID, the asset cannot be registered in the game's asset registry.

Mistake 2: Incorrect Type values

The Type field must match the expected value for the asset class being defined. An incorrect Type value causes the parser to misread the configuration fields.

Mistake 3: GUID collisions

Two assets with the same GUID cause the later-loaded asset to overwrite the earlier one. Generate fresh GUIDs for every new asset and never reuse GUIDs.

Mistake 4: ID collisions

Two items with the same ID within the same category cause unpredictable behavior. Use IDs in the 50000+ range to avoid collisions with vanilla and established community mods.

Mistake 5: Invalid field values

Field values must match their expected types. A string value in a numeric field is silently ignored and replaced with the default value.

Mistake 6: Unbalanced braces

Dictionaries opened with { must be closed with }. Lists opened with [ must be closed with ]. Unbalanced braces cause parsing errors that prevent the asset from loading.

Mistake 7: Incorrect master bundle pointers

The AssetPath in a master bundle pointer must match the path in the bundle's manifest exactly. Even a single-character difference causes the reference to fail.

Mistake 8: Missing localization files

Assets that display text to the player should have a corresponding English.dat file. Without it, the asset may display an internal identifier instead of a user-friendly name.

Design patterns

The completeness pattern

Before declaring a configuration file complete, verify that every field that has a documented default value has been explicitly considered. Some fields should use their defaults; others need explicit values. The decision should be intentional.

The documentation pattern

Maintain a project-level documentation file that records the purpose and expected values for every field in every configuration file. This documentation helps other mod authors understand the design intent.

The version control pattern

Store all configuration files in a version control system (Git). Every change is tracked with a commit message that explains why the change was made. This creates a complete history of the project's evolution.

The peer review pattern

Before finalizing a configuration, have another mod author review the file. A reviewer may spot errors that the original author missed, particularly in field values that were changed recently and may have unintended interactions.

Frequently asked questions (continued)

How do I know if my configuration file is correct?

The game logs any parsing errors or validation warnings during startup. Check the console output after launching the game. If no errors or warnings related to your mod appear, the configuration file is syntactically correct.

What happens when a field is omitted from a configuration file?

The parser assigns the default value for that field. Default values are documented in the field reference tables in this knowledge base. If you omit a field, the behavior may not match your intent.

Can I include comments in configuration files?

Yes. Lines starting with // are treated as comments. Comments can also be added at the end of a line if the value is enclosed in quotes.

How do I create a minimal configuration file?

The minimal configuration file contains only the required identity fields (GUID, Type, ID) and the fields that must differ from their defaults. All other fields use their default values.

What is the difference between a .dat file and an .asset file?

.dat files use the original Unturned key-value pair format. .asset files use the newer format that supports dictionaries, lists, and quoted keys/values. Both formats are valid and the parser handles both.

Glossary

Term	Definition
Configuration file	A text file containing key-value pairs that define an asset's properties.
Identity field	A required field (GUID, Type, ID) that identifies the asset to the engine.
Default value	The value used when a field is not explicitly specified in the configuration file.
Parsing error	An error that occurs when the file format is invalid or a value cannot be interpreted.
Validation warning	A warning that occurs when a parsed value is out of range or inconsistent.
Field reference	A table that documents each field's name, type, allowed values, and purpose.
Asset registry	The game's in-memory database of all loaded assets.
Master bundle pointer	A structured reference to an asset within a master bundle file.
Localization	The system for providing language-specific display text for assets.
Template	A pre-written configuration file with placeholder values.

Implementation roadmap

Phase 1: Research

Read the relevant reference article for the asset type. Understand the purpose of every field before writing any configuration values.

Phase 2: Planning

List the required and optional fields that need values. Determine the correct values based on the intended behavior.

Phase 3: Authoring

Create the configuration file. Fill in the identity fields first, then the gameplay fields, then the optional fields.

Phase 4: Validation

Check the configuration file for syntax errors. Verify that all braces and brackets are balanced. Confirm that all values match their expected types.

Phase 5: Testing

Place the configuration file in the mod directory. Launch the game and check for errors. Test the asset's behavior in-game.

Phase 6: Iteration

Adjust field values based on testing feedback. Repeat phases 4 and 5 until the behavior matches the intended design.

Authoring checklist

Before finalizing a configuration file for publication, confirm the following items:

• [ ] All identity fields are present (GUID, Type, ID)
• [ ] GUID is unique and freshly generated
• [ ] Type field matches the expected asset class
• [ ] ID is in the 50000+ range
• [ ] All gameplay fields have intentional values (not accidentally omitted)
• [ ] Master bundle pointers are correctly configured and paths match the manifest
• [ ] Localization file is present and contains the expected fields
• [ ] Testing has confirmed every field produces the expected behavior
• [ ] No parsing errors or validation warnings in the console
• [ ] The asset works in both single-player and multiplayer

Server-specific advanced topics

Server optimization for modded content

When running a server with multiple mods, optimize performance by bundling related assets together in fewer master bundles. Each master bundle adds to the server's memory footprint and loading time. Combine small mods into shared bundles where possible.

Server security with custom configurations

Custom server configurations should never expose sensitive information such as GSLT tokens or admin Steam IDs in publicly accessible files. Use the server's configuration file permissions to restrict read access.

Server update planning

Plan server updates to minimize player disruption. Schedule updates during low-traffic periods. Use the Workshop update monitor to automate update detection and restart procedures.

Troubleshooting guide

Problem: Server fails to start

If the dedicated server fails to start, check the console for error messages. Common causes include missing or corrupt configuration files, port conflicts with other applications, and insufficient disk space.

Problem: Players cannot connect

If players cannot connect to the server, check firewall settings, port forwarding configuration, and GSLT token validity. Verify that the server is running on the expected IP address and port.

Problem: Mods fail to load on the server

If mods load in single-player but not on the dedicated server, check that the mod files are in the correct directory on the server. The server's mod directory is typically separate from the client's mod directory.

Problem: Server performance degradation

If the server experiences performance degradation after adding mods, check the server resource usage (CPU, memory, disk I/O). Remove mods one at a time to identify which mod is causing the issue.

Frequently asked questions (continued)

How do I back up my server configuration?

Copy the entire Servers directory to a backup location. The directory contains all configuration files, save data, and logs. Back up before making significant configuration changes.

Can I run a server without a GSLT?

Yes, but the server will not appear on the Internet server list. Players can only join through the server code or Steam friends list.

What ports need to be open for Unturned servers?

The default ports are UDP 27015 (query port) and 27016 (game traffic port). These must be forwarded in the router and allowed through the firewall.

How many servers can I run on one machine?

The practical limit depends on the machine's hardware. Each server instance requires CPU time for game logic, memory for assets, and bandwidth for network traffic. A dedicated server machine can typically run 2-5 instances.

Should I use a static IP for my server?

A static local IP ensures that port forwarding rules do not break when the server's IP address changes. Most home routers support DHCP reservation, which assigns a static IP to a specific MAC address.

Configuration file management

Version numbering

Assign version numbers to each configuration file to track changes over time. Include the version number in a comment at the top of the file. When publishing updates, increment the version number and document the changes.

Change documentation

Maintain a changelog file alongside the configuration files. Record the date, version, author, and description of each change. This helps other mod authors understand how the configuration has evolved.

File naming conventions

Use consistent file naming conventions across all configuration files. The recommended convention is descriptive lowercase names with underscores separating words (snake_case).

Frequently asked questions (continued)

How do I roll back a configuration change?

Restore the previous version from version control. If version control is not in use, restore from a manual backup. This is why version control is strongly recommended.

What information should I include in a changelog entry?

Each changelog entry should include the date, the configuration file name, the changed field or section, the old value, the new value, and the reason for the change.

How do I share configuration best practices with my team?

Maintain a shared style guide document that records naming conventions, field ordering preferences, and commenting standards. Review pull requests to ensure compliance.

Operational considerations

Monitoring server health

Regularly check the server's resource usage (CPU, memory, disk space) to ensure it can handle the current player load. Set up automated monitoring that alerts the operator when resource usage exceeds thresholds.

Log management

The server generates log files that can grow large over time. Configure log rotation to archive old logs and free disk space. Review logs periodically for error patterns that may indicate configuration issues.

Player communication

Keep players informed about server maintenance, updates, and rule changes through in-game announcements, Discord, or a website. Clear communication reduces confusion and support requests.

Frequently asked questions (continued)

What should I do if a configuration file becomes corrupt?

Restore the file from the most recent backup. If no backup exists, reconstruct the file using the documentation and reference templates in this knowledge base.

How often should I back up server configuration files?

Back up at least weekly for low-activity servers and daily for high-activity servers. Always back up before making configuration changes.

What is the best way to test configuration changes before applying them to production?

Use a staging server that mirrors the production configuration. Test changes on the staging server first. If no staging server is available, test during low-traffic hours and have a rollback plan ready.

Cross-references

• Setting Up an Unturned Server - previous article.
• Server Hosting Rules - next article.
• Game Server Login Tokens - GSLT configuration.
• Fake IP Configuration - Internet server networking.

Document history

Version	Date	Author	Notes
1.0	2026-07-26	57 Studios	Initial publication. Complete SteamCMD server setup, installation on Windows and Linux, batch script creation, automation, troubleshooting.