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// Other services

Port 1761: cft-0

Port 1761 is assigned by IANA to cft-0 (cft-0).

1761

How cft-0 works

Other services
client:1761cft-0response client:1761cft-0response

The client sends a request to port 1761 and the cft-0 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 1761 dangerous?

We have no specific security note for port 1761. 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 1761

ServicePortTransportDescriptionReferenceUpdated
cft-0 1761 TCP, UDP cft-0 - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 1761, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1761'      # process listening on 1761
sudo lsof -nP -i :1761

macOS

sudo lsof -nP -i :1761

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1761 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1761
netstat -ano | findstr :1761

From another machine

nmap -p 1761 -sV <host>
sudo nmap -sU -p 1761 <host>
nc -zv <host> 1761

Block it in the firewall

sudo ufw deny 1761/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1761" -Direction Inbound -LocalPort 1761 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1761 used for?

Port 1761 is assigned by IANA to cft-0 (cft-0).

Is port 1761 TCP or UDP?

Port 1761 is registered for TCP and UDP.

Is it safe to open port 1761?

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 1761 is open?

On Linux run "ss -ltnup 'sport = :1761'", on macOS "lsof -nP -i :1761", and on Windows "netstat -ano | findstr :1761" to see the local process. From another machine, "nmap -p 1761 <host>" shows whether it is reachable.

05 Related
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