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// Network services

Port 3937: DVB Service Discovery

Port 3937 is assigned by IANA to dvbservdsc (DVB Service Discovery).

3937

How dvbservdsc works

Network services
client:3937dvbservdscresponse client:3937dvbservdscresponse

The client sends a request to port 3937 and the dvbservdsc 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
Network services
01 Security

Is port 3937 dangerous?

We have no specific security note for port 3937. Its risk depends on the program actually listening on it. General advice for network services services:

  • Answer only the networks that need the service (no open resolvers, relays or reflectors).
  • UDP services can be abused for DDoS amplification: rate-limit or block them at the edge.
  • Disable legacy test services that have no use in production.
02 Registry

IANA registry entries for port 3937

ServicePortTransportDescriptionReferenceUpdated
dvbservdsc 3937 TCP, UDP DVB Service Discovery - 2003-11

// source: IANA service name and port number registry

03 Check it

Which program uses port 3937, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3937'      # process listening on 3937
sudo lsof -nP -i :3937

macOS

sudo lsof -nP -i :3937

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3937 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3937
netstat -ano | findstr :3937

From another machine

nmap -p 3937 -sV <host>
sudo nmap -sU -p 3937 <host>
nc -zv <host> 3937

Block it in the firewall

sudo ufw deny 3937/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3937" -Direction Inbound -LocalPort 3937 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3937 used for?

Port 3937 is assigned by IANA to dvbservdsc (DVB Service Discovery).

Is port 3937 TCP or UDP?

Port 3937 is registered for TCP and UDP.

Is it safe to open port 3937?

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. Answer only the networks that need the service (no open resolvers, relays or reflectors).

How do I check if port 3937 is open?

On Linux run "ss -ltnup 'sport = :3937'", on macOS "lsof -nP -i :3937", and on Windows "netstat -ano | findstr :3937" to see the local process. From another machine, "nmap -p 3937 <host>" shows whether it is reachable.

05 Related
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