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// Other services

Port 3935: SDP Port Mapper Protocol

Port 3935 is assigned by IANA to sdp-portmapper (SDP Port Mapper Protocol).

3935

How sdp-portmapper works

Other services
client:3935sdp-portmapperresponse client:3935sdp-portmapperresponse

The client sends a request to port 3935 and the sdp-portmapper 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 3935 dangerous?

We have no specific security note for port 3935. 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 3935

ServicePortTransportDescriptionReferenceUpdated
sdp-portmapper 3935 TCP, UDP SDP Port Mapper Protocol - 2003-11

// source: IANA service name and port number registry

03 Check it

Which program uses port 3935, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3935'      # process listening on 3935
sudo lsof -nP -i :3935

macOS

sudo lsof -nP -i :3935

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3935 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3935
netstat -ano | findstr :3935

From another machine

nmap -p 3935 -sV <host>
sudo nmap -sU -p 3935 <host>
nc -zv <host> 3935

Block it in the firewall

sudo ufw deny 3935/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3935" -Direction Inbound -LocalPort 3935 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3935 used for?

Port 3935 is assigned by IANA to sdp-portmapper (SDP Port Mapper Protocol).

Is port 3935 TCP or UDP?

Port 3935 is registered for TCP and UDP.

Is it safe to open port 3935?

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 3935 is open?

On Linux run "ss -ltnup 'sport = :3935'", on macOS "lsof -nP -i :3935", and on Windows "netstat -ano | findstr :3935" to see the local process. From another machine, "nmap -p 3935 <host>" shows whether it is reachable.

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