CyberHunter
Local dataset, no network
// Other services

Port 2757: CNRP

Port 2757 is assigned by IANA to cnrp (CNRP).

2757

How cnrp works

Other services
client:2757cnrpresponse client:2757cnrpresponse

The client sends a request to port 2757 and the cnrp 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 2757 dangerous?

We have no specific security note for port 2757. 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 2757

ServicePortTransportDescriptionReferenceUpdated
cnrp 2757 TCP, UDP CNRP - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 2757, and is it reachable?

Linux

sudo ss -ltnup 'sport = :2757'      # process listening on 2757
sudo lsof -nP -i :2757

macOS

sudo lsof -nP -i :2757

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 2757 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 2757
netstat -ano | findstr :2757

From another machine

nmap -p 2757 -sV <host>
sudo nmap -sU -p 2757 <host>
nc -zv <host> 2757

Block it in the firewall

sudo ufw deny 2757/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 2757" -Direction Inbound -LocalPort 2757 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 2757 used for?

Port 2757 is assigned by IANA to cnrp (CNRP).

Is port 2757 TCP or UDP?

Port 2757 is registered for TCP and UDP.

Is it safe to open port 2757?

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 2757 is open?

On Linux run "ss -ltnup 'sport = :2757'", on macOS "lsof -nP -i :2757", and on Windows "netstat -ano | findstr :2757" to see the local process. From another machine, "nmap -p 2757 <host>" shows whether it is reachable.

05 Related
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