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// Other services

Port 93: Device Control Protocol

Port 93 is assigned by IANA to dcp (Device Control Protocol).

93

How dcp works

Other services
client:93dcpresponse client:93dcpresponse

The client sends a request to port 93 and the dcp 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
Well-known (0-1023)
Category
Other services
01 Security

Is port 93 dangerous?

We have no specific security note for port 93. 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 93

ServicePortTransportDescriptionReferenceUpdated
dcp 93 TCP, UDP Device Control Protocol - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 93, and is it reachable?

Linux

sudo ss -ltnup 'sport = :93'      # process listening on 93
sudo lsof -nP -i :93

macOS

sudo lsof -nP -i :93

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 93 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 93
netstat -ano | findstr :93

From another machine

nmap -p 93 -sV <host>
sudo nmap -sU -p 93 <host>
nc -zv <host> 93

Block it in the firewall

sudo ufw deny 93/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 93" -Direction Inbound -LocalPort 93 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 93 used for?

Port 93 is assigned by IANA to dcp (Device Control Protocol).

Is port 93 TCP or UDP?

Port 93 is registered for TCP and UDP.

Is it safe to open port 93?

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 93 is open?

On Linux run "ss -ltnup 'sport = :93'", on macOS "lsof -nP -i :93", and on Windows "netstat -ano | findstr :93" to see the local process. From another machine, "nmap -p 93 <host>" shows whether it is reachable.

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