Port 25565 Minecraft · TCP

What runs on port 25565

Minecraft Java Edition server (Bedrock uses UDP 19132). The most-forwarded port on home routers, with a corresponding tail of exposed servers running old versions; the 2021 Log4Shell vulnerability was exploited through Minecraft chat first. Keep the server updated, use a whitelist, and consider a proxy (Velocity, Bungee) or a hosting service.

Software that uses it: Minecraft Java server · Paper, Spigot, Fabric servers · Velocity / BungeeCord (proxies)

Should port 25565 be open?

Designed to face the internet. This port exists to be reachable from anywhere, so the usual question is not whether to open it but how the service behind it is configured and patched.

• mcstatus or the server list in the client shows whether it is reachable; online-mode=true keeps authentication with Mojang on.

Check port 25565

# on the host: is anything listening, and which process?
ss -ltnp 'sport = :25565'
sudo lsof -i :25565

# from another machine: is it reachable?
nc -zv host 25565
nmap -p 25565 host
curl -v telnet://host:25565      # raw TCP connect test, Ctrl-C to leave

A port that answers from the internet when it should not is the finding; nmap from a machine outside your network (or a VPS) is the honest test, because scans from inside the LAN pass the firewall you are trying to verify.

Allow or block port 25565

# ufw (Ubuntu/Debian)
sudo ufw allow from 10.0.0.0/8 to any port 25565 proto tcp
sudo ufw deny 25565/tcp

# nftables
nft add rule inet filter input ip saddr 10.0.0.0/8 tcp dport 25565 accept
nft add rule inet filter input tcp dport 25565 drop

# iptables (legacy)
iptables -A INPUT -p tcp --dport 25565 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 25565 -j DROP

# firewalld
sudo firewall-cmd --permanent --add-rich-rule='rule family=ipv4 source address=10.0.0.0/8 port port=25565 protocol=tcp accept'

Replace 10.0.0.0/8 with the networks that need access. Allowing by source address is the rule that matters; "allow 25565" with no source is just "open".

Related ports

• 27015 Source engine games

Part of the port number reference. Ports are 16-bit numbers; see also the subnet calculator and the packet decoder, which shows ports inside TCP and UDP headers.

Questions