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// Other services

Port 731: IBM NetView DM/6000 receive/tcp

Port 731 is assigned by IANA to netviewdm3 (IBM NetView DM/6000 receive/tcp).

731

How netviewdm3 works

Other services
client:731netviewdm3response client:731netviewdm3response

The client sends a request to port 731 and the netviewdm3 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 731 dangerous?

We have no specific security note for port 731. 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 731

ServicePortTransportDescriptionReferenceUpdated
netviewdm3 731 TCP, UDP IBM NetView DM/6000 receive/tcp - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 731, and is it reachable?

Linux

sudo ss -ltnup 'sport = :731'      # process listening on 731
sudo lsof -nP -i :731

macOS

sudo lsof -nP -i :731

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 731 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 731
netstat -ano | findstr :731

From another machine

nmap -p 731 -sV <host>
sudo nmap -sU -p 731 <host>
nc -zv <host> 731

Block it in the firewall

sudo ufw deny 731/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 731" -Direction Inbound -LocalPort 731 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 731 used for?

Port 731 is assigned by IANA to netviewdm3 (IBM NetView DM/6000 receive/tcp).

Is port 731 TCP or UDP?

Port 731 is registered for TCP and UDP.

Is it safe to open port 731?

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 731 is open?

On Linux run "ss -ltnup 'sport = :731'", on macOS "lsof -nP -i :731", and on Windows "netstat -ano | findstr :731" to see the local process. From another machine, "nmap -p 731 <host>" shows whether it is reachable.

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