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Port 669 (meregister)

IANA assigns port 669 to meregister: MeRegister.

Well-known (system) port, 0-1023 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
meregister TCP MeRegister Armin Sawusch -
meregister UDP MeRegister Armin Sawusch -

Check what is listening on port 669

Linux: is anything listening on TCP 669?
sudo ss -tlnp 'sport = :669'
Linux: UDP 669
sudo ss -ulnp 'sport = :669'
Linux / macOS: which process owns the port
sudo lsof -nP -i :669
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':669 '
Windows (Command Prompt)
netstat -ano | findstr :669
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 669 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 669
From Windows
Test-NetConnection HOST -Port 669
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 669

Block port 669 in the firewall

ufw
sudo ufw deny 669/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 669 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 669 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 669' -Direction Inbound -Protocol TCP -LocalPort 669 -Action Block
ufw
sudo ufw deny 669/udp
iptables
sudo iptables -A INPUT -p udp --dport 669 -j DROP
nftables
sudo nft add rule inet filter input udp dport 669 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 669' -Direction Inbound -Protocol UDP -LocalPort 669 -Action Block

Related ports

667disclose668mecomm670vacdsm-sws671vacdsm-app

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