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// Other services

Port 27000: FLEX LM (1-10)

Port 27000 is assigned by IANA to flex-lm (FLEX LM (1-10)).

27000

How flex-lm works

Other services
client:27000flex-lmresponse client:27000flex-lmresponse

The client sends a request to port 27000 and the flex-lm service answers.

Transport
None registered
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 27000 dangerous?

We have no specific security note for port 27000. 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 27000

ServicePortTransportDescriptionReferenceUpdated
flex-lm 27000-27009 - FLEX LM (1-10) - 2018-02-15

// source: IANA service name and port number registry

03 Check it

Which program uses port 27000, and is it reachable?

Linux

sudo ss -ltnup 'sport = :27000'      # process listening on 27000
sudo lsof -nP -i :27000

macOS

sudo lsof -nP -i :27000

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 27000 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 27000
netstat -ano | findstr :27000

From another machine

nmap -p 27000 -sV <host>
nc -zv <host> 27000

Block it in the firewall

sudo ufw deny 27000/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 27000" -Direction Inbound -LocalPort 27000 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 27000 used for?

Port 27000 is assigned by IANA to flex-lm (FLEX LM (1-10)).

Is port 27000 TCP or UDP?

Port 27000 has no registered transport. Any program can still use it over TCP or UDP.

Is it safe to open port 27000?

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 27000 is open?

On Linux run "ss -ltnup 'sport = :27000'", on macOS "lsof -nP -i :27000", and on Windows "netstat -ano | findstr :27000" to see the local process. From another machine, "nmap -p 27000 <host>" shows whether it is reachable.

05 Related
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