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// Other services

Port 771:

Port 771 is assigned by IANA to rtip ().

771

How rtip works

Other services
client:771rtipresponse client:771rtipresponse

The client sends a request to port 771 and the rtip 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
01 Security

Is port 771 dangerous?

We have no specific security note for port 771. 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 771

ServicePortTransportDescriptionReferenceUpdated
rtip 771 TCP, UDP - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 771, and is it reachable?

Linux

sudo ss -ltnup 'sport = :771'      # process listening on 771
sudo lsof -nP -i :771

macOS

sudo lsof -nP -i :771

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 771 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 771
netstat -ano | findstr :771

From another machine

nmap -p 771 -sV <host>
sudo nmap -sU -p 771 <host>
nc -zv <host> 771

Block it in the firewall

sudo ufw deny 771/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 771" -Direction Inbound -LocalPort 771 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 771 used for?

Port 771 is assigned by IANA to rtip ().

Is port 771 TCP or UDP?

Port 771 is registered for TCP and UDP.

Is it safe to open port 771?

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 771 is open?

On Linux run "ss -ltnup 'sport = :771'", on macOS "lsof -nP -i :771", and on Windows "netstat -ano | findstr :771" to see the local process. From another machine, "nmap -p 771 <host>" shows whether it is reachable.

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