Port 4369 (Erlang Port Mapper (EPMD))

Erlang epmd, used by RabbitMQ, CouchDB, ejabberd and Elixir clusters to find node ports.

Registered (user) port, 1024-49151 TCP Message queues Do not expose to the internet

What port 4369 is used for

Erlang epmd, used by RabbitMQ, CouchDB, ejabberd and Elixir clusters to find node ports.

Security: should port 4369 be open?

Do not expose to the internet. Together with the distribution port and a guessed or default Erlang cookie, it gives remote code execution. Firewall it and set a strong cookie.

IANA assignment

Service nameProtoDescriptionAssigneeReference

epmd TCP Erlang Port Mapper Daemon Erlang -

epmd UDP Erlang Port Mapper Daemon Erlang -

Check what is listening on port 4369

Linux: is anything listening on TCP 4369?

sudo ss -tlnp 'sport = :4369'

Linux / macOS: which process owns the port

sudo lsof -nP -i :4369

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':4369 '

Windows (Command Prompt)

netstat -ano | findstr :4369

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 4369 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine

nc -vz -w 5 HOST 4369

From Windows

Test-NetConnection HOST -Port 4369

Block port 4369 in the firewall

ufw

sudo ufw deny 4369/tcp

iptables

sudo iptables -A INPUT -p tcp --dport 4369 -j DROP

nftables

sudo nft add rule inet filter input tcp dport 4369 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block TCP 4369' -Direction Inbound -Protocol TCP -LocalPort 4369 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.