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// Other services

Port 1804: ENL

Port 1804 is assigned by IANA to enl (ENL).

1804

How enl works

Other services
client:1804enlresponse client:1804enlresponse

The client sends a request to port 1804 and the enl service answers.

Transport
TCP · 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
Other services
01 Security

Is port 1804 dangerous?

We have no specific security note for port 1804. Its risk depends on the program actually listening on it. General advice for other services services:

  • Close the port if nothing on the host needs it.
  • Identify the process that listens on it (commands below) before opening it in a firewall.
  • Expose a service only to the networks that use it.
02 Registry

IANA registry entries for port 1804

ServicePortTransportDescriptionReferenceUpdated
enl 1804 TCP, UDP ENL - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 1804, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1804'      # process listening on 1804
sudo lsof -nP -i :1804

macOS

sudo lsof -nP -i :1804

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1804 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1804
netstat -ano | findstr :1804

From another machine

nmap -p 1804 -sV <host>
sudo nmap -sU -p 1804 <host>
nc -zv <host> 1804

Block it in the firewall

sudo ufw deny 1804/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1804" -Direction Inbound -LocalPort 1804 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1804 used for?

Port 1804 is assigned by IANA to enl (ENL).

Is port 1804 TCP or UDP?

Port 1804 is registered for TCP and UDP.

Is it safe to open port 1804?

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. Close the port if nothing on the host needs it.

How do I check if port 1804 is open?

On Linux run "ss -ltnup 'sport = :1804'", on macOS "lsof -nP -i :1804", and on Windows "netstat -ano | findstr :1804" to see the local process. From another machine, "nmap -p 1804 <host>" shows whether it is reachable.

05 Related
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