Editing Service Location Protocol (section)

== Security ==
SLP contains a security mechanism, based on [[public key|public-key cryptography]], that allows signing of service announcements. In practice it is rarely used:
* The public keys of every service provider must be installed on every UA. This requirement defeats the original purpose of SLP, being able to locate services without prior configuration.
* Protecting only the services is not enough. Service URLs contain host names or IP addresses, and in a local network it is almost impossible to prevent [[Internet protocol spoofing|IP or DNS spoofing]]. Thus only guaranteeing the authenticity of the URL is not enough if any device can respond to the address.
* As addresses can be spoofed, the authenticity of the device must be proven at a different level anyway, e.g. in the application protocol (e.g. with [[Secure Sockets Layer|SSL]]) or in the packet layer ([[IPsec]]). Doing it additionally in SLP does not provide much additional security.