Port 16379 (TCP) — Redis Cluster bus: explained

Port 16379 Redis Cluster bus · TCP

Redis Cluster bus port: each node's data port plus 10000 (6379 → 16379).

Port	16379
Transport	TCP
Service	Redis Cluster bus — Data port + 10000
Category	Databases and caches
Range	registered (1024–49151)
Encrypted	No, plaintext
Exposure	Private network or VPN only

What runs on port 16379

Redis Cluster bus port: each node's data port plus 10000 (6379 → 16379). Nodes gossip and fail over through it; it must be open between cluster members and nowhere else.

Software that uses it: Redis Cluster · Valkey Cluster

Should port 16379 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.

CLUSTERDOWN with healthy nodes usually means the bus port is blocked between them.

Check port 16379

# on the host: is anything listening, and which process?
ss -ltnp 'sport = :16379'
sudo lsof -i :16379

# from another machine: is it reachable?
nc -zv host 16379
nmap -p 16379 host
curl -v telnet://host:16379      # 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 16379

# ufw (Ubuntu/Debian)
sudo ufw allow from 10.0.0.0/8 to any port 16379 proto tcp
sudo ufw deny 16379/tcp

# nftables
nft add rule inet filter input ip saddr 10.0.0.0/8 tcp dport 16379 accept
nft add rule inet filter input tcp dport 16379 drop

# iptables (legacy)
iptables -A INPUT -p tcp --dport 16379 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 16379 -j DROP

# firewalld
sudo firewall-cmd --permanent --add-rich-rule='rule family=ipv4 source address=10.0.0.0/8 port port=16379 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 16379" with no source is just "open".

Related ports

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

Is port 16379 TCP or UDP?

TCP. Redis Cluster bus is a connection-oriented protocol; there is no UDP service on 16379 by default (a scanner reporting UDP 16379 open is usually seeing a filtered port).

Is port 16379 encrypted?

No, plaintext. Anything sent over it can be read by whoever is on the path, so it belongs on a trusted network or inside a VPN or SSH tunnel.

How do I check whether port 16379 is open?

On the server, ss -ltnp (or -lunp for UDP) shows whether something listens on 16379 and which process. From another machine, nc -zv host 16379 or nmap -p 16379 host tests reachability. "Open" in a scan means something answered; a firewall usually makes the port filtered (no answer) rather than closed (RST).

Can Redis Cluster bus run on a different port?

Yes; the number is a convention, not a requirement. Changing it reduces log noise from scanners but does not add security, and every client, firewall rule and monitoring check then needs the new number. Keep the default unless you have a concrete reason.