CyberHunter
Local dataset, no network
// Other services

Port 3923: Symbian Service Broker

Port 3923 is assigned by IANA to symb-sb-port (Symbian Service Broker).

3923

How symb-sb-port works

Other services
client:3923symb-sb-portresponse client:3923symb-sb-portresponse

The client sends a request to port 3923 and the symb-sb-port 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 3923 dangerous?

We have no specific security note for port 3923. 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 3923

ServicePortTransportDescriptionReferenceUpdated
symb-sb-port 3923 TCP, UDP Symbian Service Broker - 2003-11

// source: IANA service name and port number registry

03 Check it

Which program uses port 3923, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3923'      # process listening on 3923
sudo lsof -nP -i :3923

macOS

sudo lsof -nP -i :3923

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3923 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3923
netstat -ano | findstr :3923

From another machine

nmap -p 3923 -sV <host>
sudo nmap -sU -p 3923 <host>
nc -zv <host> 3923

Block it in the firewall

sudo ufw deny 3923/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3923" -Direction Inbound -LocalPort 3923 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3923 used for?

Port 3923 is assigned by IANA to symb-sb-port (Symbian Service Broker).

Is port 3923 TCP or UDP?

Port 3923 is registered for TCP and UDP.

Is it safe to open port 3923?

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 3923 is open?

On Linux run "ss -ltnup 'sport = :3923'", on macOS "lsof -nP -i :3923", and on Windows "netstat -ano | findstr :3923" to see the local process. From another machine, "nmap -p 3923 <host>" shows whether it is reachable.

05 Related
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