CyberHunter
Local dataset, no network
// Other services

Port 31620: lm mon

Port 31620 is assigned by IANA to lm-mon (lm mon).

31620

How lm-mon works

Other services
client:31620lm-monresponse client:31620lm-monresponse

The client sends a request to port 31620 and the lm-mon 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 31620 dangerous?

We have no specific security note for port 31620. 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 31620

ServicePortTransportDescriptionReferenceUpdated
lm-mon 31620 TCP, UDP lm mon - 2003-06

// source: IANA service name and port number registry

03 Check it

Which program uses port 31620, and is it reachable?

Linux

sudo ss -ltnup 'sport = :31620'      # process listening on 31620
sudo lsof -nP -i :31620

macOS

sudo lsof -nP -i :31620

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 31620 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 31620
netstat -ano | findstr :31620

From another machine

nmap -p 31620 -sV <host>
sudo nmap -sU -p 31620 <host>
nc -zv <host> 31620

Block it in the firewall

sudo ufw deny 31620/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 31620" -Direction Inbound -LocalPort 31620 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 31620 used for?

Port 31620 is assigned by IANA to lm-mon (lm mon).

Is port 31620 TCP or UDP?

Port 31620 is registered for TCP and UDP.

Is it safe to open port 31620?

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 31620 is open?

On Linux run "ss -ltnup 'sport = :31620'", on macOS "lsof -nP -i :31620", and on Windows "netstat -ano | findstr :31620" to see the local process. From another machine, "nmap -p 31620 <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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