- Serve it over HTTPS only and check the HTTP security headers.
- Keep admin consoles and development servers off the Internet.
- Patch the application server and remove default credentials and sample apps.
Port 20003: Commtact HTTPS
Port 20003 is assigned by IANA to commtact-https (Commtact HTTPS).
20003
How commtact-https works
WebA browser sends an HTTP request to port 20003 and the commtact-https server sends the page back.
- 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
- Web
Is port 20003 dangerous?
We have no specific security note for port 20003. Its risk depends on the program actually listening on it. General advice for web services:
IANA registry entries for port 20003
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| commtact-https | 20003 | TCP, UDP | Commtact HTTPS | - | 2004-12 |
// source: IANA service name and port number registry
Which program uses port 20003, and is it reachable?
Linux
sudo ss -ltnup 'sport = :20003' # process listening on 20003
sudo lsof -nP -i :20003macOS
sudo lsof -nP -i :20003
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 20003 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 20003 netstat -ano | findstr :20003
From another machine
nmap -p 20003 -sV <host> sudo nmap -sU -p 20003 <host> nc -zv <host> 20003
Block it in the firewall
sudo ufw deny 20003/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 20003" -Direction Inbound -LocalPort 20003 -Protocol TCP -Action Block # Windows
What is port 20003 used for?
Port 20003 is assigned by IANA to commtact-https (Commtact HTTPS).
Is port 20003 TCP or UDP?
Port 20003 is registered for TCP and UDP.
Is it safe to open port 20003?
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. Serve it over HTTPS only and check the HTTP security headers.
How do I check if port 20003 is open?
On Linux run "ss -ltnup 'sport = :20003'", on macOS "lsof -nP -i :20003", and on Windows "netstat -ano | findstr :20003" to see the local process. From another machine, "nmap -p 20003 <host>" shows whether it is reachable.
Other web ports
: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