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Port 3665 (ent-engine)

IANA assigns port 3665 to ent-engine: Enterprise Engine Port.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
ent-engine TCP Enterprise Engine Port Mike Delgrosso -
ent-engine UDP Enterprise Engine Port Mike Delgrosso -

Registry dates for this port: registered 2003-01.

Check what is listening on port 3665

Linux: is anything listening on TCP 3665?
sudo ss -tlnp 'sport = :3665'
Linux: UDP 3665
sudo ss -ulnp 'sport = :3665'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3665
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3665 '
Windows (Command Prompt)
netstat -ano | findstr :3665
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3665 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3665
From Windows
Test-NetConnection HOST -Port 3665
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3665

Block port 3665 in the firewall

ufw
sudo ufw deny 3665/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3665 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3665 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3665' -Direction Inbound -Protocol TCP -LocalPort 3665 -Action Block
ufw
sudo ufw deny 3665/udp
iptables
sudo iptables -A INPUT -p udp --dport 3665 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3665 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3665' -Direction Inbound -Protocol UDP -LocalPort 3665 -Action Block

Related ports

3663dtp3664ups-engine3666eserver-pap3667infoexch

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