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Port 4394 (apwi-disc)

IANA assigns port 4394 to apwi-disc: American Printware Discovery.

Registered (user) port, 1024-49151 UDP

Port 4394 is normally used over UDP; the checker tests TCP only, so a "filtered" result does not mean the UDP service is down.

IANA assignment

Service nameProtoDescriptionAssigneeReference
apwi-disc UDP American Printware Discovery Lech Lakomy -

Registry dates for this port: registered 2009-02-12.

Check what is listening on port 4394

Linux: UDP 4394
sudo ss -ulnp 'sport = :4394'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4394
Windows (Command Prompt)
netstat -ano | findstr :4394
Windows (PowerShell)
Get-NetUDPEndpoint -LocalPort 4394

Test it from outside

UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4394

Block port 4394 in the firewall

ufw
sudo ufw deny 4394/udp
iptables
sudo iptables -A INPUT -p udp --dport 4394 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4394 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4394' -Direction Inbound -Protocol UDP -LocalPort 4394 -Action Block

Related ports

4392apwi-rxserver4393apwi-rxspooler4395omnivisionesx4396fly

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