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Port 19999 (dnp-sec)

IANA assigns port 19999 to dnp-sec: Distributed Network Protocol - Secure.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
dnp-sec TCP Distributed Network Protocol - Secure Grant Gilchrist -
dnp-sec UDP Distributed Network Protocol - Secure Grant Gilchrist -
dnp-sec SCTP Distributed Network Protocol - secured DNP Users Group -

Registry dates for this port: registered 2008-08-04.

Check what is listening on port 19999

Linux: is anything listening on TCP 19999?
sudo ss -tlnp 'sport = :19999'
Linux: UDP 19999
sudo ss -ulnp 'sport = :19999'
Linux / macOS: which process owns the port
sudo lsof -nP -i :19999
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':19999 '
Windows (Command Prompt)
netstat -ano | findstr :19999
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 19999 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 19999
From Windows
Test-NetConnection HOST -Port 19999
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 19999

Block port 19999 in the firewall

ufw
sudo ufw deny 19999/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 19999 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 19999 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 19999' -Direction Inbound -Protocol TCP -LocalPort 19999 -Action Block
ufw
sudo ufw deny 19999/udp
iptables
sudo iptables -A INPUT -p udp --dport 19999 -j DROP
nftables
sudo nft add rule inet filter input udp dport 19999 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 19999' -Direction Inbound -Protocol UDP -LocalPort 19999 -Action Block

Related ports

19790faircom-db19998iec-104-sec20000DNP320001microsan

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