CyberHunter
// Other services

Port 3765: Remote Traceroute

Port 3765 is assigned by IANA to rtraceroute (Remote Traceroute).

3765

How rtraceroute works

Other services
client:3765rtracerouteresponse client:3765rtracerouteresponse

The client sends a request to port 3765 and the rtraceroute 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)
01 Security

Is port 3765 dangerous?

We have no specific security note for port 3765. 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 3765

ServicePortTransportDescriptionReferenceUpdated
rtraceroute 3765 TCP, UDP Remote Traceroute - 2003-06

// source: IANA service name and port number registry

03 Check it

Which program uses port 3765, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3765'      # process listening on 3765
sudo lsof -nP -i :3765

macOS

sudo lsof -nP -i :3765

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3765 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3765
netstat -ano | findstr :3765

From another machine

nmap -p 3765 -sV <host>
sudo nmap -sU -p 3765 <host>
nc -zv <host> 3765

Block it in the firewall

sudo ufw deny 3765/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3765" -Direction Inbound -LocalPort 3765 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3765 used for?

Port 3765 is assigned by IANA to rtraceroute (Remote Traceroute).

Is port 3765 TCP or UDP?

Port 3765 is registered for TCP and UDP.

Is it safe to open port 3765?

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 3765 is open?

On Linux run "ss -ltnup 'sport = :3765'", on macOS "lsof -nP -i :3765", and on Windows "netstat -ano | findstr :3765" to see the local process. From another machine, "nmap -p 3765 <host>" shows whether it is reachable.

05 Related