UPnP / SSDP
What is Port 1900?
Port 1900 is used by the Simple Service Discovery Protocol (SSDP), the discovery component of Universal Plug and Play (UPnP). UPnP allows devices on a local network to automatically discover each other and establish network services without manual configuration. SSDP uses HTTP-like messages sent to the multicast address 239.255.255.250 on port 1900. Devices announce their presence and capabilities, and other devices can search for specific services. UPnP is used by media servers, game consoles, smart TVs, printers, routers, and IoT devices. When you stream music from your phone to a Chromecast or DLNA speaker, UPnP/SSDP facilitates the initial device discovery.
Common Uses
- Media device discovery (DLNA, Chromecast)
- Smart TV and streaming device setup
- Router automatic port forwarding
- IoT device auto-configuration
Technical Details
Copy-paste commands to check port 1900 (UPnP / SSDP) from your terminal
Test connectivity
nmap -p 1900 -sU -sV example.com
(echo > /dev/tcp/example.com/1900) 2>/dev/null && echo "open" || echo "closed"
Open port in firewall
sudo ufw allow 1900/udp
sudo iptables -A INPUT -p udp --dport 1900 -j ACCEPT
sudo firewall-cmd --permanent --add-port=1900/udp && sudo firewall-cmd --reload
Security Considerations
UPnP is a significant security risk. UPnP-enabled routers can be tricked into opening firewall ports from internal malware without user interaction. SSDP has been exploited for massive DDoS amplification attacks. Disable UPnP on your router unless absolutely needed. Never expose port 1900 to the internet. Use manual port forwarding instead of UPnP when possible.
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