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Port 446 (ddm-rdb)

IANA assigns port 446 to ddm-rdb: DDM-Remote Relational Database Access.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
ddm-rdb TCP DDM-Remote Relational Database Access - -
ddm-rdb UDP DDM-Remote Relational Database Access - -

Check what is listening on port 446

Linux: is anything listening on TCP 446?
sudo ss -tlnp 'sport = :446'
Linux: UDP 446
sudo ss -ulnp 'sport = :446'
Linux / macOS: which process owns the port
sudo lsof -nP -i :446
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':446 '
Windows (Command Prompt)
netstat -ano | findstr :446
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 446 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 446
From Windows
Test-NetConnection HOST -Port 446
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 446

Block port 446 in the firewall

ufw
sudo ufw deny 446/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 446 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 446 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 446' -Direction Inbound -Protocol TCP -LocalPort 446 -Action Block
ufw
sudo ufw deny 446/udp
iptables
sudo iptables -A INPUT -p udp --dport 446 -j DROP
nftables
sudo nft add rule inet filter input udp dport 446 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 446' -Direction Inbound -Protocol UDP -LocalPort 446 -Action Block

Related ports

444snpp445SMB (Microsoft-DS)447ddm-dfm448ddm-ssl

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