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// Other services

Port 1421: Gandalf License Manager

Port 1421 is assigned by IANA to gandalf-lm (Gandalf License Manager).

1421

How gandalf-lm works

Other services
client:1421gandalf-lmresponse client:1421gandalf-lmresponse

The client sends a request to port 1421 and the gandalf-lm 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 1421 dangerous?

We have no specific security note for port 1421. 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 1421

ServicePortTransportDescriptionReferenceUpdated
gandalf-lm 1421 TCP, UDP Gandalf License Manager - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 1421, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1421'      # process listening on 1421
sudo lsof -nP -i :1421

macOS

sudo lsof -nP -i :1421

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1421 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1421
netstat -ano | findstr :1421

From another machine

nmap -p 1421 -sV <host>
sudo nmap -sU -p 1421 <host>
nc -zv <host> 1421

Block it in the firewall

sudo ufw deny 1421/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1421" -Direction Inbound -LocalPort 1421 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1421 used for?

Port 1421 is assigned by IANA to gandalf-lm (Gandalf License Manager).

Is port 1421 TCP or UDP?

Port 1421 is registered for TCP and UDP.

Is it safe to open port 1421?

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 1421 is open?

On Linux run "ss -ltnup 'sport = :1421'", on macOS "lsof -nP -i :1421", and on Windows "netstat -ano | findstr :1421" to see the local process. From another machine, "nmap -p 1421 <host>" shows whether it is reachable.

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