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// Other services

Port 393: Meta5

Port 393 is assigned by IANA to meta5 (Meta5).

393

How meta5 works

Other services
client:393meta5response client:393meta5response

The client sends a request to port 393 and the meta5 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
Well-known (0-1023)
Category
Other services
01 Security

Is port 393 dangerous?

We have no specific security note for port 393. 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 393

ServicePortTransportDescriptionReferenceUpdated
meta5 393 TCP, UDP Meta5 - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 393, and is it reachable?

Linux

sudo ss -ltnup 'sport = :393'      # process listening on 393
sudo lsof -nP -i :393

macOS

sudo lsof -nP -i :393

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 393 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 393
netstat -ano | findstr :393

From another machine

nmap -p 393 -sV <host>
sudo nmap -sU -p 393 <host>
nc -zv <host> 393

Block it in the firewall

sudo ufw deny 393/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 393" -Direction Inbound -LocalPort 393 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 393 used for?

Port 393 is assigned by IANA to meta5 (Meta5).

Is port 393 TCP or UDP?

Port 393 is registered for TCP and UDP.

Is it safe to open port 393?

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 393 is open?

On Linux run "ss -ltnup 'sport = :393'", on macOS "lsof -nP -i :393", and on Windows "netstat -ano | findstr :393" to see the local process. From another machine, "nmap -p 393 <host>" shows whether it is reachable.

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