CyberHunter
Local dataset, no network
// Other services

Port 3855: OpenTRAC

Port 3855 is assigned by IANA to opentrac (OpenTRAC).

3855

How opentrac works

Other services
client:3855opentracresponse client:3855opentracresponse

The client sends a request to port 3855 and the opentrac 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 3855 dangerous?

We have no specific security note for port 3855. 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 3855

ServicePortTransportDescriptionReferenceUpdated
opentrac 3855 TCP, UDP OpenTRAC - 2003-08

// source: IANA service name and port number registry

03 Check it

Which program uses port 3855, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3855'      # process listening on 3855
sudo lsof -nP -i :3855

macOS

sudo lsof -nP -i :3855

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3855 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3855
netstat -ano | findstr :3855

From another machine

nmap -p 3855 -sV <host>
sudo nmap -sU -p 3855 <host>
nc -zv <host> 3855

Block it in the firewall

sudo ufw deny 3855/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3855" -Direction Inbound -LocalPort 3855 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3855 used for?

Port 3855 is assigned by IANA to opentrac (OpenTRAC).

Is port 3855 TCP or UDP?

Port 3855 is registered for TCP and UDP.

Is it safe to open port 3855?

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 3855 is open?

On Linux run "ss -ltnup 'sport = :3855'", on macOS "lsof -nP -i :3855", and on Windows "netstat -ano | findstr :3855" to see the local process. From another machine, "nmap -p 3855 <host>" shows whether it is reachable.

05 Related
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