CyberHunter
Local dataset, no network
// Other services

Port 5251: CA eTrust VM Service

Port 5251 is assigned by IANA to caevms (CA eTrust VM Service).

5251

How caevms works

Other services
client:5251caevmsresponse client:5251caevmsresponse

The client sends a request to port 5251 and the caevms 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 5251 dangerous?

We have no specific security note for port 5251. 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 5251

ServicePortTransportDescriptionReferenceUpdated
caevms 5251 TCP, UDP CA eTrust VM Service - 2004-11

// source: IANA service name and port number registry

03 Check it

Which program uses port 5251, and is it reachable?

Linux

sudo ss -ltnup 'sport = :5251'      # process listening on 5251
sudo lsof -nP -i :5251

macOS

sudo lsof -nP -i :5251

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 5251 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 5251
netstat -ano | findstr :5251

From another machine

nmap -p 5251 -sV <host>
sudo nmap -sU -p 5251 <host>
nc -zv <host> 5251

Block it in the firewall

sudo ufw deny 5251/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 5251" -Direction Inbound -LocalPort 5251 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 5251 used for?

Port 5251 is assigned by IANA to caevms (CA eTrust VM Service).

Is port 5251 TCP or UDP?

Port 5251 is registered for TCP and UDP.

Is it safe to open port 5251?

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 5251 is open?

On Linux run "ss -ltnup 'sport = :5251'", on macOS "lsof -nP -i :5251", and on Windows "netstat -ano | findstr :5251" to see the local process. From another machine, "nmap -p 5251 <host>" shows whether it is reachable.

05 Related
:4444 Metasploit default / krb524 tcp · udp · high risk :31337 Back Orifice / elite tcp · udp · high risk :1 TCP Port Service Multiplexer tcp · udp :5 Remote Job Entry tcp · udp :9 Discard tcp · udp · sctp · dccp :11 Active Users tcp · udp :17 Quote of the Day tcp · udp :18 Message Send Protocol (historic) tcp · udp

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