Port 7946 (Docker Swarm / Serf gossip)

Node discovery and gossip in Docker Swarm, Serf, Consul (LAN gossip uses 8301) and MetalLB.

Registered (user) port, 1024-49151 TCPUDP Containers and Kubernetes Do not expose to the internet

What port 7946 is used for

Node discovery and gossip in Docker Swarm, Serf, Consul (LAN gossip uses 8301) and MetalLB.

Do not expose to the internet. Cluster nodes only.

Port 7946 is in the registered range and has no IANA assignment. The usage above is unofficial but widespread.

Linux: is anything listening on TCP 7946?

sudo ss -tlnp 'sport = :7946'

Linux: UDP 7946

sudo ss -ulnp 'sport = :7946'

Linux / macOS: which process owns the port

sudo lsof -nP -i :7946

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':7946 '

Windows (Command Prompt)

netstat -ano | findstr :7946

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 7946 -State Listen | Select LocalAddress,OwningProcess

From another machine

nc -vz -w 5 HOST 7946

From Windows

Test-NetConnection HOST -Port 7946

UDP probe (no reply does not prove it is closed)

nc -vzu -w 5 HOST 7946

ufw

sudo ufw deny 7946/tcp

iptables

sudo iptables -A INPUT -p tcp --dport 7946 -j DROP

nftables

sudo nft add rule inet filter input tcp dport 7946 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block TCP 7946' -Direction Inbound -Protocol TCP -LocalPort 7946 -Action Block

ufw

sudo ufw deny 7946/udp

iptables

sudo iptables -A INPUT -p udp --dport 7946 -j DROP

nftables

sudo nft add rule inet filter input udp dport 7946 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block UDP 7946' -Direction Inbound -Protocol UDP -LocalPort 7946 -Action Block

All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.