name: minecraft-modpack-server

description: Set up a modded Minecraft server from a CurseForge/Modrinth server pack zip. Covers NeoForge/Forge install, Java version, JVM tuning, firewall, LAN config, backups, and launch scripts.

tags: [minecraft, gaming, server, neoforge, forge, modpack]

Minecraft Modpack Server Setup

When to use

• - User wants to set up a modded Minecraft server from a server pack zip
• - User needs help with NeoForge/Forge server configuration
• - User asks about Minecraft server performance tuning or backups

Gather User Preferences First

Before starting setup, ask the user for:

• - Server name / MOTD — what should it say in the server list?
• - Seed — specific seed or random?
• - Difficulty — peaceful / easy / normal / hard?
• - Gamemode — survival / creative / adventure?
• - Online mode — true (Mojang auth, legit accounts) or false (LAN/cracked friendly)?
• - Player count — how many players expected? (affects RAM & view distance tuning)
• - RAM allocation — or let agent decide based on mod count & available RAM?
• - View distance / simulation distance — or let agent pick based on player count & hardware?
• - PvP — on or off?
• - Whitelist — open server or whitelist only?
• - Backups — want automated backups? How often?

Use sensible defaults if the user doesn't care, but always ask before generating the config.

Steps

1. Download & Inspect the Pack

`bash

mkdir -p ~/minecraft-server

cd ~/minecraft-server

wget -O serverpack.zip ""

unzip -o serverpack.zip -d server

ls server/

`

Look for: startserver.sh, installer jar (neoforge/forge), user_jvm_args.txt, mods/ folder.

Check the script to determine: mod loader type, version, and required Java version.

2. Install Java

• - Minecraft 1.21+ → Java 21: sudo apt install openjdk-21-jre-headless
• - Minecraft 1.18-1.20 → Java 17: sudo apt install openjdk-17-jre-headless
• - Minecraft 1.16 and below → Java 8: sudo apt install openjdk-8-jre-headless
• - Verify: java -version

3. Install the Mod Loader

Most server packs include an install script. Use the INSTALL_ONLY env var to install without launching:

`bash

cd ~/minecraft-server/server

ATM10_INSTALL_ONLY=true bash startserver.sh

Or for generic Forge packs:

java -jar forge-*-installer.jar --installServer

`

This downloads libraries, patches the server jar, etc.

4. Accept EULA

`bash

echo "eula=true" > ~/minecraft-server/server/eula.txt

`

5. Configure server.properties

Key settings for modded/LAN:

`properties

motd=\u00a7b\u00a7lServer Name \u00a7r\u00a78| \u00a7aModpack Name

server-port=25565

online-mode=true # false for LAN without Mojang auth

enforce-secure-profile=true # match online-mode

difficulty=hard # most modpacks balance around hard

allow-flight=true # REQUIRED for modded (flying mounts/items)

spawn-protection=0 # let everyone build at spawn

max-tick-time=180000 # modded needs longer tick timeout

enable-command-block=true

`

Performance settings (scale to hardware):

`properties

2 players, beefy machine:

view-distance=16

simulation-distance=10

4-6 players, moderate machine:

view-distance=10

simulation-distance=6

8+ players or weaker hardware:

view-distance=8

simulation-distance=4

`

6. Tune JVM Args (user_jvm_args.txt)

Scale RAM to player count and mod count. Rule of thumb for modded:

• - 100-200 mods: 6-12GB
• - 200-350+ mods: 12-24GB
• - Leave at least 8GB free for the OS/other tasks

`

-Xms12G

-Xmx24G

-XX:+UseG1GC

-XX:+ParallelRefProcEnabled

-XX:MaxGCPauseMillis=200

-XX:+UnlockExperimentalVMOptions

-XX:+DisableExplicitGC

-XX:+AlwaysPreTouch

-XX:G1NewSizePercent=30

-XX:G1MaxNewSizePercent=40

-XX:G1HeapRegionSize=8M

-XX:G1ReservePercent=20

-XX:G1HeapWastePercent=5

-XX:G1MixedGCCountTarget=4

-XX:InitiatingHeapOccupancyPercent=15

-XX:G1MixedGCLiveThresholdPercent=90

-XX:G1RSetUpdatingPauseTimePercent=5

-XX:SurvivorRatio=32

-XX:+PerfDisableSharedMem

-XX:MaxTenuringThreshold=1

`

7. Open Firewall

`bash

sudo ufw allow 25565/tcp comment "Minecraft Server"

`

Check with: sudo ufw status | grep 25565

8. Create Launch Script

`bash

cat > ~/start-minecraft.sh << 'EOF'

#!/bin/bash

cd ~/minecraft-server/server

java @user_jvm_args.txt @libraries/net/neoforged/neoforge//unix_args.txt nogui

EOF

chmod +x ~/start-minecraft.sh

`

Note: For Forge (not NeoForge), the args file path differs. Check startserver.sh for the exact path.

9. Set Up Automated Backups

Create backup script:

`bash

cat > ~/minecraft-server/backup.sh << 'SCRIPT'

#!/bin/bash

SERVER_DIR="$HOME/minecraft-server/server"

BACKUP_DIR="$HOME/minecraft-server/backups"

WORLD_DIR="$SERVER_DIR/world"

MAX_BACKUPS=24

mkdir -p "$BACKUP_DIR"

[ ! -d "$WORLD_DIR" ] && echo "[BACKUP] No world folder" && exit 0

TIMESTAMP=$(date +%Y-%m-%d_%H-%M-%S)

BACKUP_FILE="$BACKUP_DIR/world_${TIMESTAMP}.tar.gz"

echo "[BACKUP] Starting at $(date)"

tar -czf "$BACKUP_FILE" -C "$SERVER_DIR" world

SIZE=$(du -h "$BACKUP_FILE" | cut -f1)

echo "[BACKUP] Saved: $BACKUP_FILE ($SIZE)"

BACKUP_COUNT=$(ls -1t "$BACKUP_DIR"/world_*.tar.gz 2>/dev/null | wc -l)

if [ "$BACKUP_COUNT" -gt "$MAX_BACKUPS" ]; then

REMOVE=$((BACKUP_COUNT - MAX_BACKUPS))

ls -1t "$BACKUP_DIR"/world_*.tar.gz | tail -n "$REMOVE" | xargs rm -f

echo "[BACKUP] Pruned $REMOVE old backup(s)"

fi

echo "[BACKUP] Done at $(date)"

SCRIPT

chmod +x ~/minecraft-server/backup.sh

`

Add hourly cron:

`bash

(crontab -l 2>/dev/null | grep -v "minecraft/backup.sh"; echo "0 $HOME/minecraft-server/backup.sh >> $HOME/minecraft-server/backups/backup.log 2>&1") | crontab -

`

Pitfalls

• - ALWAYS set allow-flight=true for modded — mods with jetpacks/flight will kick players otherwise
• - max-tick-time=180000 or higher — modded servers often have long ticks during worldgen
• - First startup is SLOW (several minutes for big packs) — don't panic
• - "Can't keep up!" warnings on first launch are normal, settles after initial chunk gen
• - If online-mode=false, set enforce-secure-profile=false too or clients get rejected
• - The pack's startserver.sh often has an auto-restart loop — make a clean launch script without it
• - Delete the world/ folder to regenerate with a new seed
• - Some packs have env vars to control behavior (e.g., ATM10 uses ATM10_JAVA, ATM10_RESTART, ATM10_INSTALL_ONLY)

Verification

• - pgrep -fa neoforge or pgrep -fa minecraft to check if running
• - Check logs: tail -f ~/minecraft-server/server/logs/latest.log
• - Look for "Done (Xs)!" in the log = server is ready
• - Test connection: player adds server IP in Multiplayer