Port 2380 (TCP) — etcd peer: what it is, how to check

Port 2380 etcd peer · TCP

etcd peer port: replication and leader election between etcd members. Only other etcd nodes should reach it.

Port	2380
Transport	TCP
Service	etcd peer
Category	Infrastructure
Range	registered (1024–49151)
Encrypted	Yes, always (TLS or equivalent)
Exposure	Private network or VPN only

What runs on port 2380

etcd peer port: replication and leader election between etcd members. Only other etcd nodes should reach it. Latency between peers matters; etcd complains above ~100 ms round trip.

Software that uses it: etcd

Should port 2380 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.

A member stuck "unhealthy" with 2380 blocked between nodes is the usual cause of a control plane that cannot elect a leader.

Check port 2380

# on the host: is anything listening, and which process?
ss -ltnp 'sport = :2380'
sudo lsof -i :2380

# from another machine: is it reachable?
nc -zv host 2380
nmap -p 2380 host
curl -v telnet://host:2380      # 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 2380

# ufw (Ubuntu/Debian)
sudo ufw allow from 10.0.0.0/8 to any port 2380 proto tcp
sudo ufw deny 2380/tcp

# nftables
nft add rule inet filter input ip saddr 10.0.0.0/8 tcp dport 2380 accept
nft add rule inet filter input tcp dport 2380 drop

# iptables (legacy)
iptables -A INPUT -p tcp --dport 2380 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 2380 -j DROP

# firewalld
sudo firewall-cmd --permanent --add-rich-rule='rule family=ipv4 source address=10.0.0.0/8 port port=2380 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 2380" 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 2380 TCP or UDP?

TCP. etcd peer is a connection-oriented protocol; there is no UDP service on 2380 by default (a scanner reporting UDP 2380 open is usually seeing a filtered port).

Is port 2380 encrypted?

Yes, always (TLS or equivalent). The port number does not make it safe by itself: certificate validation, authentication and patching still decide.

How do I check whether port 2380 is open?

On the server, ss -ltnp (or -lunp for UDP) shows whether something listens on 2380 and which process. From another machine, nc -zv host 2380 or nmap -p 2380 host tests reachability. "Open" in a scan means something answered; a firewall usually makes the port filtered (no answer) rather than closed (RST).

Can etcd peer 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.