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// Other services

Port 3813: Rhapsody Interface Protocol

Port 3813 is assigned by IANA to rap-ip (Rhapsody Interface Protocol).

3813

How rap-ip works

Other services
client:3813rap-ipresponse client:3813rap-ipresponse

The client sends a request to port 3813 and the rap-ip 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 3813 dangerous?

We have no specific security note for port 3813. 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 3813

ServicePortTransportDescriptionReferenceUpdated
rap-ip 3813 TCP, UDP Rhapsody Interface Protocol - 2004-03

// source: IANA service name and port number registry

03 Check it

Which program uses port 3813, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3813'      # process listening on 3813
sudo lsof -nP -i :3813

macOS

sudo lsof -nP -i :3813

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3813 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3813
netstat -ano | findstr :3813

From another machine

nmap -p 3813 -sV <host>
sudo nmap -sU -p 3813 <host>
nc -zv <host> 3813

Block it in the firewall

sudo ufw deny 3813/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3813" -Direction Inbound -LocalPort 3813 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3813 used for?

Port 3813 is assigned by IANA to rap-ip (Rhapsody Interface Protocol).

Is port 3813 TCP or UDP?

Port 3813 is registered for TCP and UDP.

Is it safe to open port 3813?

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 3813 is open?

On Linux run "ss -ltnup 'sport = :3813'", on macOS "lsof -nP -i :3813", and on Windows "netstat -ano | findstr :3813" to see the local process. From another machine, "nmap -p 3813 <host>" shows whether it is reachable.

05 Related
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