Port 25672 RabbitMQ inter-node · TCP

What runs on port 25672

RabbitMQ inter-node and CLI tool communication (the Erlang distribution port, 20000 + 5672). Needed between cluster members and from hosts that run rabbitmqctl remotely; firewalled from everything else.

Software that uses it: RabbitMQ

Should port 25672 be open?

Private network or VPN only. Nothing good comes from this port being reachable from the internet. Keep it on an internal network, reach it over a VPN or an SSH tunnel, and firewall it from everything that does not need it.

• Together with 4369 this is the set a RabbitMQ cluster needs between nodes.

Check port 25672

# on the host: is anything listening, and which process?
ss -ltnp 'sport = :25672'
sudo lsof -i :25672

# from another machine: is it reachable?
nc -zv host 25672
nmap -p 25672 host
curl -v telnet://host:25672      # 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 25672

# ufw (Ubuntu/Debian)
sudo ufw allow from 10.0.0.0/8 to any port 25672 proto tcp
sudo ufw deny 25672/tcp

# nftables
nft add rule inet filter input ip saddr 10.0.0.0/8 tcp dport 25672 accept
nft add rule inet filter input tcp dport 25672 drop

# iptables (legacy)
iptables -A INPUT -p tcp --dport 25672 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 25672 -j DROP

# firewalld
sudo firewall-cmd --permanent --add-rich-rule='rule family=ipv4 source address=10.0.0.0/8 port port=25672 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 25672" with no source is just "open".

Related ports

• 5672 AMQP — RabbitMQ
• 4369 EPMD — Erlang port mapper (RabbitMQ)
• 15672 RabbitMQ management

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