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// Network services

Port 4394: American Printware Discovery

Port 4394 is assigned by IANA to apwi-disc (American Printware Discovery).

4394

How apwi-disc works

Network services
client:4394apwi-discresponse client:4394apwi-discresponse

The client sends a request to port 4394 and the apwi-disc service answers.

Transport
UDP
Exposure risk
not rated depends on the program listening
Encryption
Unknownnot stated by the registry
IANA status
Assigned1 registered service
Range
Registered (1024-49151)
Category
Network services
01 Security

Is port 4394 dangerous?

We have no specific security note for port 4394. Its risk depends on the program actually listening on it. General advice for network services services:

  • Answer only the networks that need the service (no open resolvers, relays or reflectors).
  • UDP services can be abused for DDoS amplification: rate-limit or block them at the edge.
  • Disable legacy test services that have no use in production.
02 Registry

IANA registry entries for port 4394

ServicePortTransportDescriptionReferenceUpdated
apwi-disc 4394 UDP American Printware Discovery - 2009-02-12
-4394-Reserved--

// source: IANA service name and port number registry

03 Check it

Which program uses port 4394, and is it reachable?

Linux

sudo ss -ltnup 'sport = :4394'      # process listening on 4394
sudo lsof -nP -i :4394

macOS

sudo lsof -nP -i :4394

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 4394 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 4394
netstat -ano | findstr :4394

From another machine

nmap -p 4394 -sV <host>
sudo nmap -sU -p 4394 <host>
nc -zv <host> 4394

Block it in the firewall

sudo ufw deny 4394/udp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 4394" -Direction Inbound -LocalPort 4394 -Protocol UDP -Action Block  # Windows
04 FAQ
What is port 4394 used for?

Port 4394 is assigned by IANA to apwi-disc (American Printware Discovery).

Is port 4394 TCP or UDP?

Port 4394 is registered for UDP.

Is it safe to open port 4394?

It depends on the program that listens on it. Open it only for a service you know and only to the networks that need it. Answer only the networks that need the service (no open resolvers, relays or reflectors).

How do I check if port 4394 is open?

On Linux run "ss -ltnup 'sport = :4394'", on macOS "lsof -nP -i :4394", and on Windows "netstat -ano | findstr :4394" to see the local process. From another machine, "nmap -p 4394 <host>" shows whether it is reachable.

05 Related
:53 DNS tcp · udp · moderate risk :135 MS RPC tcp · udp · high risk :123 NTP udp · tcp · moderate risk :67 DHCP server udp · tcp · moderate risk :111 rpcbind tcp · udp · high risk :9100 Raw printing (JetDirect) tcp · udp · high risk :631 IPP / CUPS tcp · udp · high risk :5353 mDNS udp · tcp · moderate risk

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