Port 1900 SSDP
Port 1900 is the IANA-assigned ssdp port for SSDP (TCP / UDP).
What is port 1900 used for?
Port 1900 is assigned to ssdp and uses TCP / UDP. The IANA registry describes the service as “SSDP”. It sits in the registered range, the block used by databases, application servers and developer tooling. Port conflicts here are common when several local services start at once.
Ports are the transport-layer address a service listens on. A client that wants to reach ssdp connects to port 1900. A TCP connection is refused when nothing is listening, while a UDP request simply goes unanswered. That is why a port conflict appears whenever two processes try to bind the same number.
Use the commands below to confirm whether port 1900 is actually in use before you change firewall rules. Blocking the port stops new inbound traffic at the firewall, but it does not stop a local process from listening, and it does not remove the service from the machine.
Browse all IoT and device telemetry ports
Source: IANA Service Name and Transport Protocol Port Number Registry. Registered assignee: [UPnP_Forum].
Check and block port 1900
Copy-ready commands for the protocols assigned to this port. Run the check first, then block only what should not be reachable.
Check on Linux
sudo ss -tlpn 'sport = :1900'
sudo ss -ulpn 'sport = :1900'Check on Windows
Get-NetTCPConnection -LocalPort 1900 -State Listen -ErrorAction SilentlyContinue
Get-NetUDPEndpoint -LocalPort 1900 -ErrorAction SilentlyContinueBlock with UFW
sudo ufw deny 1900/tcp
sudo ufw deny 1900/udpBlock with iptables
sudo iptables -A INPUT -p tcp --dport 1900 -j DROP
sudo iptables -A INPUT -p udp --dport 1900 -j DROPThese commands are examples for a typical host. Check the listener before you change firewall rules, and persist iptables rules with iptables-save or netfilter-persistent. On Windows, use Windows Defender Firewall or New-NetFirewallRule for persistent blocks. The iptables rules here cover IPv4; mirror them with ip6tables if IPv6 is enabled.
Is port 1900 safe to expose?
UPnP has a long history of router vulnerabilities and can let untrusted devices open firewall holes. Disable it where possible. Expose this port only when the service is actually needed. Keep it patched, prefer an encrypted alternative, and limit source addresses with a firewall allowlist.
Where port 1900 is usually used
Most traffic on port 1900 falls into these scenarios. The demo below is a safe way to confirm the listener before you change anything.
- Sensors publishing telemetry to a broker or gateway.
- Home-automation or industrial devices subscribing to commands.
- Testing device connectivity with a protocol client instead of a browser.
Confirm the SSDP listener
SSDP uses UDP multicast, so a TCP probe proves nothing. Check the local UDP socket or watch for SSDP traffic.
sudo ss -ulpn 'sport = :1900'Common problems with port 1900
Connection refused or timed out
Refused usually means the host is reachable but nothing is listening on port 1900. A timeout more often means a firewall drop, a wrong host or a service bound to a different interface.
Port already in use
Find the process holding the port with sudo ss -tlpn 'sport = :1900' or sudo lsof -i :1900. Stop that process or configure it to bind another port; killing it without identifying it can take down a production service.
Firewall rule did not survive a reboot
UFW and Windows Firewall keep rules across restarts. Raw iptables rules do not: save them with iptables-save or the netfilter-persistent package, and re-apply after upgrades that reset the ruleset.
The port is blocked but still reachable
A firewall rule filters inbound traffic; it does not close the listener. Confirm with the check command above and bind the service to 127.0.0.1 when only local clients need it.
Port 1900 at a glance
| Port number | 1900 |
|---|---|
| Service name | ssdp |
| Transport protocol | TCP / UDP |
| Category | IoT and device telemetry |
| Range | Registered port (1024–10000) |
| Risk level | Medium |
| Registered assignee | [UPnP_Forum] |
| Registry description | SSDP |
| Source | IANA Service Name and Transport Protocol Port Number Registry |
Frequently asked questions
What is port 1900 used for?
Port 1900 (SSDP) uses TCP / UDP. SSDP.
How do I check if port 1900 is open?
On Linux run `sudo ss -tlpn 'sport = :1900'` and `sudo ss -ulpn 'sport = :1900'`. On Windows run `Get-NetTCPConnection -LocalPort 1900 -State Listen -ErrorAction SilentlyContinue` and `Get-NetUDPEndpoint -LocalPort 1900 -ErrorAction SilentlyContinue` in PowerShell. If the port is open, the output shows a process listening on port 1900; empty output usually means nothing is bound to it.
How do I block port 1900?
With UFW run `sudo ufw deny 1900/tcp` and `sudo ufw deny 1900/udp`. With iptables run `sudo iptables -A INPUT -p tcp --dport 1900 -j DROP` and `sudo iptables -A INPUT -p udp --dport 1900 -j DROP`. Persist the iptables rules with your distribution's netfilter-persistent or iptables-save tooling so they survive a reboot.
Is port 1900 safe to expose?
UPnP has a long history of router vulnerabilities and can let untrusted devices open firewall holes. Disable it where possible. Nevertheless, expose this port only when the service is actually needed. Keep it patched, prefer an encrypted alternative, and limit source addresses with a firewall allowlist.
Related ports
- Port 1896 · b-novative-lsb-novative license server
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- Port 5087 · bioticBIOTIC - Binary Internet of Things Interoperable Communication
- Port 5683 · coapConstrained Application Protocol (CoAP)
- Port 5684 · coapsConstrained Application Protocol (CoAP)
- Port 17754 · zepEncap. ZigBee Packets
Primary data: IANA Service Name and Transport Protocol Port Number Registry.
Last reviewed 2026-10-30 · Methodology · About · Privacy