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Port 8666 (monetra-admin)

IANA assigns port 8666 to monetra-admin: Monetra Administrative Access.

Registered (user) port, 1024-49151 TCP

IANA assignment

Service nameProtoDescriptionAssigneeReference
monetra-admin TCP Monetra Administrative Access Main Street Softworks -

Registry dates for this port: registered 2013-04-02.

Check what is listening on port 8666

Linux: is anything listening on TCP 8666?
sudo ss -tlnp 'sport = :8666'
Linux / macOS: which process owns the port
sudo lsof -nP -i :8666
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':8666 '
Windows (Command Prompt)
netstat -ano | findstr :8666
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 8666 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 8666
From Windows
Test-NetConnection HOST -Port 8666

Block port 8666 in the firewall

ufw
sudo ufw deny 8666/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 8666 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 8666 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 8666' -Direction Inbound -Protocol TCP -LocalPort 8666 -Action Block

Related ports

8615imink8665monetra8668spartan8675msi-cps-rm, msi-cps-rm-disc

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