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// Other services

Port 1647: rsap

Port 1647 is assigned by IANA to rsap (rsap).

1647

How rsap works

Other services
client:1647rsapresponse client:1647rsapresponse

The client sends a request to port 1647 and the rsap 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 1647 dangerous?

We have no specific security note for port 1647. 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 1647

ServicePortTransportDescriptionReferenceUpdated
rsap 1647 TCP, UDP rsap - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 1647, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1647'      # process listening on 1647
sudo lsof -nP -i :1647

macOS

sudo lsof -nP -i :1647

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1647 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1647
netstat -ano | findstr :1647

From another machine

nmap -p 1647 -sV <host>
sudo nmap -sU -p 1647 <host>
nc -zv <host> 1647

Block it in the firewall

sudo ufw deny 1647/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1647" -Direction Inbound -LocalPort 1647 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1647 used for?

Port 1647 is assigned by IANA to rsap (rsap).

Is port 1647 TCP or UDP?

Port 1647 is registered for TCP and UDP.

Is it safe to open port 1647?

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 1647 is open?

On Linux run "ss -ltnup 'sport = :1647'", on macOS "lsof -nP -i :1647", and on Windows "netstat -ano | findstr :1647" to see the local process. From another machine, "nmap -p 1647 <host>" shows whether it is reachable.

05 Related
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