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// Other services

Port 390: UIS

Port 390 is assigned by IANA to uis (UIS).

390

How uis works

Other services
client:390uisresponse client:390uisresponse

The client sends a request to port 390 and the uis 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 390 dangerous?

We have no specific security note for port 390. 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 390

ServicePortTransportDescriptionReferenceUpdated
uis 390 TCP, UDP UIS - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 390, and is it reachable?

Linux

sudo ss -ltnup 'sport = :390'      # process listening on 390
sudo lsof -nP -i :390

macOS

sudo lsof -nP -i :390

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 390 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 390
netstat -ano | findstr :390

From another machine

nmap -p 390 -sV <host>
sudo nmap -sU -p 390 <host>
nc -zv <host> 390

Block it in the firewall

sudo ufw deny 390/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 390" -Direction Inbound -LocalPort 390 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 390 used for?

Port 390 is assigned by IANA to uis (UIS).

Is port 390 TCP or UDP?

Port 390 is registered for TCP and UDP.

Is it safe to open port 390?

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 390 is open?

On Linux run "ss -ltnup 'sport = :390'", on macOS "lsof -nP -i :390", and on Windows "netstat -ano | findstr :390" to see the local process. From another machine, "nmap -p 390 <host>" shows whether it is reachable.

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