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Port 4089 (opencore)

IANA assigns port 4089 to opencore: OpenCORE Remote Control Service.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
opencore TCP OpenCORE Remote Control Service Pim van Riezen -
opencore UDP OpenCORE Remote Control Service Pim van Riezen -

Registry dates for this port: registered 2006-07.

Check what is listening on port 4089

Linux: is anything listening on TCP 4089?
sudo ss -tlnp 'sport = :4089'
Linux: UDP 4089
sudo ss -ulnp 'sport = :4089'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4089
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4089 '
Windows (Command Prompt)
netstat -ano | findstr :4089
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4089 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4089
From Windows
Test-NetConnection HOST -Port 4089
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4089

Block port 4089 in the firewall

ufw
sudo ufw deny 4089/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4089 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4089 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4089' -Direction Inbound -Protocol TCP -LocalPort 4089 -Action Block
ufw
sudo ufw deny 4089/udp
iptables
sudo iptables -A INPUT -p udp --dport 4089 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4089 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4089' -Direction Inbound -Protocol UDP -LocalPort 4089 -Action Block

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