HTTPfy

Port 665 (sun-dr)

IANA assigns port 665 to sun-dr: Sun DR.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
sun-dr TCP Sun DR Harinder Bhasin -
sun-dr UDP Sun DR Harinder Bhasin -

Check what is listening on port 665

Linux: is anything listening on TCP 665?
sudo ss -tlnp 'sport = :665'
Linux: UDP 665
sudo ss -ulnp 'sport = :665'
Linux / macOS: which process owns the port
sudo lsof -nP -i :665
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':665 '
Windows (Command Prompt)
netstat -ano | findstr :665
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 665 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 665
From Windows
Test-NetConnection HOST -Port 665
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 665

Block port 665 in the firewall

ufw
sudo ufw deny 665/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 665 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 665 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 665' -Direction Inbound -Protocol TCP -LocalPort 665 -Action Block
ufw
sudo ufw deny 665/udp
iptables
sudo iptables -A INPUT -p udp --dport 665 -j DROP
nftables
sudo nft add rule inet filter input udp dport 665 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 665' -Direction Inbound -Protocol UDP -LocalPort 665 -Action Block

Related ports

663purenoise664oob-ws-https, asf-secure-rmcp666doom667disclose

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