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// Web

Port 9443: HTTPS alternate (admin)

Alternate HTTPS port used by admin consoles (Portainer, VMware and others).

Portainer HTTPSvSphere
9443

How HTTPS alternate (admin) works

Web
browser:9443#%&@!x9? browser:9443#%&@!x9?

A browser sends an HTTP request to port 9443 and the HTTPS alternate (admin) server sends the page back. Everything is encrypted: someone on the path only sees unreadable bytes.

Transport
TCP · UDP
Exposure risk
5/10 moderate if reachable from the Internet
Encryption
EncryptedTLS or built-in crypto
IANA status
Assignedcommon use differs from the registry
Range
Registered (1024-49151)
Category
Web
01 Security

Is port 9443 dangerous?

Common attacks and weaknesses

  • Management interfaces targeted by critical CVEs.

How to secure it

  • Restrict to admin networks.

Unofficial use. The IANA assignment below differs from what is usually found on this port in practice.

02 Registry

IANA registry entries for port 9443

ServicePortTransportDescriptionReferenceUpdated
tungsten-https 9443 TCP, UDP WSO2 Tungsten HTTPS - 2006-06

// source: IANA service name and port number registry

03 Check it

Which program uses port 9443, and is it reachable?

Linux

sudo ss -ltnup 'sport = :9443'      # process listening on 9443
sudo lsof -nP -i :9443

macOS

sudo lsof -nP -i :9443

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 9443 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 9443
netstat -ano | findstr :9443

From another machine

nmap -p 9443 -sV <host>
sudo nmap -sU -p 9443 <host>
nc -zv <host> 9443

Block it in the firewall

sudo ufw deny 9443/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 9443" -Direction Inbound -LocalPort 9443 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 9443 used for?

Alternate HTTPS port used by admin consoles (Portainer, VMware and others).

Is port 9443 TCP or UDP?

Port 9443 is registered for TCP and UDP. In practice the service mostly uses TCP.

Is it safe to open port 9443?

It is rated 5/10 (moderate) when exposed to the Internet. Management interfaces targeted by critical CVEs. Restrict to admin networks.

How do I check if port 9443 is open?

On Linux run "ss -ltnup 'sport = :9443'", on macOS "lsof -nP -i :9443", and on Windows "netstat -ano | findstr :9443" to see the local process. From another machine, "nmap -p 9443 <host>" shows whether it is reachable.

05 Related
:443 HTTPS tcp · udp · sctp · low risk :80 HTTP tcp · udp · sctp · moderate risk :8080 HTTP alternate tcp · udp · high risk :8443 HTTPS alternate tcp · udp · moderate risk :3000 Dev servers / Grafana tcp · udp · moderate risk :5000 Flask / Docker registry / UPnP tcp · udp · moderate risk :8000 HTTP alternate (dev) tcp · udp · moderate risk :8888 Jupyter / HTTP alternate tcp · udp · high risk

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