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// Other services

Port 1765: cft-4

Port 1765 is assigned by IANA to cft-4 (cft-4).

1765

How cft-4 works

Other services
client:1765cft-4response client:1765cft-4response

The client sends a request to port 1765 and the cft-4 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 1765 dangerous?

We have no specific security note for port 1765. 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 1765

ServicePortTransportDescriptionReferenceUpdated
cft-4 1765 TCP, UDP cft-4 - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 1765, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1765'      # process listening on 1765
sudo lsof -nP -i :1765

macOS

sudo lsof -nP -i :1765

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1765 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1765
netstat -ano | findstr :1765

From another machine

nmap -p 1765 -sV <host>
sudo nmap -sU -p 1765 <host>
nc -zv <host> 1765

Block it in the firewall

sudo ufw deny 1765/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1765" -Direction Inbound -LocalPort 1765 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1765 used for?

Port 1765 is assigned by IANA to cft-4 (cft-4).

Is port 1765 TCP or UDP?

Port 1765 is registered for TCP and UDP.

Is it safe to open port 1765?

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 1765 is open?

On Linux run "ss -ltnup 'sport = :1765'", on macOS "lsof -nP -i :1765", and on Windows "netstat -ano | findstr :1765" to see the local process. From another machine, "nmap -p 1765 <host>" shows whether it is reachable.

05 Related
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