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// Other services

Port 246: Display Systems Protocol

Port 246 is assigned by IANA to dsp3270 (Display Systems Protocol).

246

How dsp3270 works

Other services
client:246dsp3270response client:246dsp3270response

The client sends a request to port 246 and the dsp3270 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 246 dangerous?

We have no specific security note for port 246. 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 246

ServicePortTransportDescriptionReferenceUpdated
dsp3270 246 TCP, UDP Display Systems Protocol - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 246, and is it reachable?

Linux

sudo ss -ltnup 'sport = :246'      # process listening on 246
sudo lsof -nP -i :246

macOS

sudo lsof -nP -i :246

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 246 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 246
netstat -ano | findstr :246

From another machine

nmap -p 246 -sV <host>
sudo nmap -sU -p 246 <host>
nc -zv <host> 246

Block it in the firewall

sudo ufw deny 246/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 246" -Direction Inbound -LocalPort 246 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 246 used for?

Port 246 is assigned by IANA to dsp3270 (Display Systems Protocol).

Is port 246 TCP or UDP?

Port 246 is registered for TCP and UDP.

Is it safe to open port 246?

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 246 is open?

On Linux run "ss -ltnup 'sport = :246'", on macOS "lsof -nP -i :246", and on Windows "netstat -ano | findstr :246" to see the local process. From another machine, "nmap -p 246 <host>" shows whether it is reachable.

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