CyberHunter
Local dataset, no network
// Other services

Port 1866: swrmi

Port 1866 is assigned by IANA to swrmi (swrmi).

1866

How swrmi works

Other services
client:1866swrmiresponse client:1866swrmiresponse

The client sends a request to port 1866 and the swrmi 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 1866 dangerous?

We have no specific security note for port 1866. 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 1866

ServicePortTransportDescriptionReferenceUpdated
swrmi 1866 TCP, UDP swrmi - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 1866, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1866'      # process listening on 1866
sudo lsof -nP -i :1866

macOS

sudo lsof -nP -i :1866

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1866 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1866
netstat -ano | findstr :1866

From another machine

nmap -p 1866 -sV <host>
sudo nmap -sU -p 1866 <host>
nc -zv <host> 1866

Block it in the firewall

sudo ufw deny 1866/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1866" -Direction Inbound -LocalPort 1866 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1866 used for?

Port 1866 is assigned by IANA to swrmi (swrmi).

Is port 1866 TCP or UDP?

Port 1866 is registered for TCP and UDP.

Is it safe to open port 1866?

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 1866 is open?

On Linux run "ss -ltnup 'sport = :1866'", on macOS "lsof -nP -i :1866", and on Windows "netstat -ano | findstr :1866" to see the local process. From another machine, "nmap -p 1866 <host>" shows whether it is reachable.

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