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// Other services

Port 2738: NDL TCP-OSI Gateway

Port 2738 is assigned by IANA to ndl-tcp-ois-gw (NDL TCP-OSI Gateway).

2738

How ndl-tcp-ois-gw works

Other services
client:2738ndl-tcp-ois-gwresponse client:2738ndl-tcp-ois-gwresponse

The client sends a request to port 2738 and the ndl-tcp-ois-gw 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 2738 dangerous?

We have no specific security note for port 2738. 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 2738

ServicePortTransportDescriptionReferenceUpdated
ndl-tcp-ois-gw 2738 TCP, UDP NDL TCP-OSI Gateway - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 2738, and is it reachable?

Linux

sudo ss -ltnup 'sport = :2738'      # process listening on 2738
sudo lsof -nP -i :2738

macOS

sudo lsof -nP -i :2738

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 2738 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 2738
netstat -ano | findstr :2738

From another machine

nmap -p 2738 -sV <host>
sudo nmap -sU -p 2738 <host>
nc -zv <host> 2738

Block it in the firewall

sudo ufw deny 2738/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 2738" -Direction Inbound -LocalPort 2738 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 2738 used for?

Port 2738 is assigned by IANA to ndl-tcp-ois-gw (NDL TCP-OSI Gateway).

Is port 2738 TCP or UDP?

Port 2738 is registered for TCP and UDP.

Is it safe to open port 2738?

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 2738 is open?

On Linux run "ss -ltnup 'sport = :2738'", on macOS "lsof -nP -i :2738", and on Windows "netstat -ano | findstr :2738" to see the local process. From another machine, "nmap -p 2738 <host>" shows whether it is reachable.

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