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Port 1819 (plato-lm)

IANA assigns port 1819 to plato-lm: Plato License Manager.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
plato-lm TCP Plato License Manager Mark Morris -
plato-lm UDP Plato License Manager Mark Morris -

Check what is listening on port 1819

Linux: is anything listening on TCP 1819?
sudo ss -tlnp 'sport = :1819'
Linux: UDP 1819
sudo ss -ulnp 'sport = :1819'
Linux / macOS: which process owns the port
sudo lsof -nP -i :1819
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':1819 '
Windows (Command Prompt)
netstat -ano | findstr :1819
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 1819 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 1819
From Windows
Test-NetConnection HOST -Port 1819
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 1819

Block port 1819 in the firewall

ufw
sudo ufw deny 1819/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 1819 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 1819 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 1819' -Direction Inbound -Protocol TCP -LocalPort 1819 -Action Block
ufw
sudo ufw deny 1819/udp
iptables
sudo iptables -A INPUT -p udp --dport 1819 -j DROP
nftables
sudo nft add rule inet filter input udp dport 1819 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 1819' -Direction Inbound -Protocol UDP -LocalPort 1819 -Action Block

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