: Port 5357 is used by SSDP, which is part of the UPnP protocol. SSDP is used for discovering UPnP devices and services on a network. This protocol is widely used in IoT devices and home networks for device discovery and service advertisement.

Port 5357 is used by the Web Services for Devices (WSD) API — a Microsoft implementation that allows networked devices (printers, scanners, cameras, IoT appliances) and Windows hosts to discover and communicate with each other over HTTP-like endpoints. Because WSD exposes device management and discovery functionality, misconfigured or exposed WSD endpoints can reveal device information, let administrators or services be manipulated remotely, or provide an entry point for lateral movement.

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: The service can leak metadata such as device hostnames, manufacturer details, and network paths. Attackers use this for fingerprinting

If you run a nmap -p5357 192.168.1.0/24 and see open , you might have stumbled upon a Windows service that is poorly understood but potentially dangerous: .

Running an aggressive service scan against a target machine frequently reveals the port associated with wsdapi .

curl -I http://<target_ip>:5357

: Hackers can exploit SSDP and UPnP for several malicious activities:

The discovery process usually begins with a multicast message over . Once a device is discovered and a handshake is completed, further communication and data exchange move to TCP port 5357 (HTTP) or TCP port 5358 (HTTPS).