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Port 40404 (sptx)

IANA assigns port 40404 to sptx: Simplify Printing TX.

Registered (user) port, 1024-49151 TCP

IANA assignment

Service nameProtoDescriptionAssigneeReference
sptx TCP Simplify Printing TX Tricerat -

Registry dates for this port: registered 2013-12-09.

Check what is listening on port 40404

Linux: is anything listening on TCP 40404?
sudo ss -tlnp 'sport = :40404'
Linux / macOS: which process owns the port
sudo lsof -nP -i :40404
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':40404 '
Windows (Command Prompt)
netstat -ano | findstr :40404
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 40404 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 40404
From Windows
Test-NetConnection HOST -Port 40404

Block port 40404 in the firewall

ufw
sudo ufw deny 40404/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 40404 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 40404 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 40404' -Direction Inbound -Protocol TCP -LocalPort 40404 -Action Block

Related ports

40000safetynetp40023k-patentssensor40841cscp40842csccredir

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