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Port 664 (oob-ws-https, asf-secure-rmcp)

IANA assigns port 664 to oob-ws-https, asf-secure-rmcp: DMTF out-of-band secure web services management protocol.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
oob-ws-https TCP DMTF out-of-band secure web services management protocol Jim Davis -
asf-secure-rmcp UDP ASF Secure Remote Management and Control Protocol Carl First -

Registry dates for this port: registered 2007-06.

Check what is listening on port 664

Linux: is anything listening on TCP 664?
sudo ss -tlnp 'sport = :664'
Linux: UDP 664
sudo ss -ulnp 'sport = :664'
Linux / macOS: which process owns the port
sudo lsof -nP -i :664
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':664 '
Windows (Command Prompt)
netstat -ano | findstr :664
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 664 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 664
From Windows
Test-NetConnection HOST -Port 664
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 664

Block port 664 in the firewall

ufw
sudo ufw deny 664/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 664 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 664 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 664' -Direction Inbound -Protocol TCP -LocalPort 664 -Action Block
ufw
sudo ufw deny 664/udp
iptables
sudo iptables -A INPUT -p udp --dport 664 -j DROP
nftables
sudo nft add rule inet filter input udp dport 664 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 664' -Direction Inbound -Protocol UDP -LocalPort 664 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.