- 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.
Port 648: Registry Registrar Protocol (RRP)
Port 648 is assigned by IANA to rrp (Registry Registrar Protocol (RRP)).
648
How rrp works
Other servicesThe client sends a request to port 648 and the rrp 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
- Well-known (0-1023)
- Category
- Other services
Is port 648 dangerous?
We have no specific security note for port 648. Its risk depends on the program actually listening on it. General advice for other services services:
IANA registry entries for port 648
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| rrp | 648 | TCP, UDP | Registry Registrar Protocol (RRP) | - | - |
// source: IANA service name and port number registry
Which program uses port 648, and is it reachable?
Linux
sudo ss -ltnup 'sport = :648' # process listening on 648
sudo lsof -nP -i :648macOS
sudo lsof -nP -i :648
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 648 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 648 netstat -ano | findstr :648
From another machine
nmap -p 648 -sV <host> sudo nmap -sU -p 648 <host> nc -zv <host> 648
Block it in the firewall
sudo ufw deny 648/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 648" -Direction Inbound -LocalPort 648 -Protocol TCP -Action Block # Windows
What is port 648 used for?
Port 648 is assigned by IANA to rrp (Registry Registrar Protocol (RRP)).
Is port 648 TCP or UDP?
Port 648 is registered for TCP and UDP.
Is it safe to open port 648?
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 648 is open?
On Linux run "ss -ltnup 'sport = :648'", on macOS "lsof -nP -i :648", and on Windows "netstat -ano | findstr :648" to see the local process. From another machine, "nmap -p 648 <host>" shows whether it is reachable.
Other other services ports
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