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// Other services

Port 4937: ATSC-M/H Service Signaling Channel

Port 4937 is assigned by IANA to atsc-mh-ssc (ATSC-M/H Service Signaling Channel).

4937

How atsc-mh-ssc works

Other services
client:4937atsc-mh-sscresponse client:4937atsc-mh-sscresponse

The client sends a request to port 4937 and the atsc-mh-ssc service answers.

Transport
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 4937 dangerous?

We have no specific security note for port 4937. 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 4937

ServicePortTransportDescriptionReferenceUpdated
atsc-mh-ssc 4937 UDP ATSC-M/H Service Signaling Channel - 2008-10-27
-4937-Reserved--

// source: IANA service name and port number registry

03 Check it

Which program uses port 4937, and is it reachable?

Linux

sudo ss -ltnup 'sport = :4937'      # process listening on 4937
sudo lsof -nP -i :4937

macOS

sudo lsof -nP -i :4937

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 4937 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 4937
netstat -ano | findstr :4937

From another machine

nmap -p 4937 -sV <host>
sudo nmap -sU -p 4937 <host>
nc -zv <host> 4937

Block it in the firewall

sudo ufw deny 4937/udp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 4937" -Direction Inbound -LocalPort 4937 -Protocol UDP -Action Block  # Windows
04 FAQ
What is port 4937 used for?

Port 4937 is assigned by IANA to atsc-mh-ssc (ATSC-M/H Service Signaling Channel).

Is port 4937 TCP or UDP?

Port 4937 is registered for UDP.

Is it safe to open port 4937?

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 4937 is open?

On Linux run "ss -ltnup 'sport = :4937'", on macOS "lsof -nP -i :4937", and on Windows "netstat -ano | findstr :4937" to see the local process. From another machine, "nmap -p 4937 <host>" shows whether it is reachable.

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