CyberHunter
Local dataset, no network
// Other services

Port 18181: OPSEC CVP

Port 18181 is assigned by IANA to opsec-cvp (OPSEC CVP).

18181

How opsec-cvp works

Other services
client:18181opsec-cvpresponse client:18181opsec-cvpresponse

The client sends a request to port 18181 and the opsec-cvp 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 18181 dangerous?

We have no specific security note for port 18181. 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 18181

ServicePortTransportDescriptionReferenceUpdated
opsec-cvp 18181 TCP, UDP OPSEC CVP - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 18181, and is it reachable?

Linux

sudo ss -ltnup 'sport = :18181'      # process listening on 18181
sudo lsof -nP -i :18181

macOS

sudo lsof -nP -i :18181

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 18181 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 18181
netstat -ano | findstr :18181

From another machine

nmap -p 18181 -sV <host>
sudo nmap -sU -p 18181 <host>
nc -zv <host> 18181

Block it in the firewall

sudo ufw deny 18181/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 18181" -Direction Inbound -LocalPort 18181 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 18181 used for?

Port 18181 is assigned by IANA to opsec-cvp (OPSEC CVP).

Is port 18181 TCP or UDP?

Port 18181 is registered for TCP and UDP.

Is it safe to open port 18181?

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 18181 is open?

On Linux run "ss -ltnup 'sport = :18181'", on macOS "lsof -nP -i :18181", and on Windows "netstat -ano | findstr :18181" to see the local process. From another machine, "nmap -p 18181 <host>" shows whether it is reachable.

05 Related
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