science

Simple Service Discovery Protocol

Simple Service Discovery Protocol is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Simple Service Discovery Protocol rather than just read about it. In short: The Simple Service Discovery Protocol (SSDP) is a network protocol, associated with the Internet protocol suite, for advertisement and discovery of network services and presence information. It accomplishes this without the assistance of server-based configuration mechanisms, such as Dynamic Host Configuration Protocol (DHCP) or the Domain Name System (DNS), and without special static configuration of a network host.

Key takeaways

Simple Service Discovery Protocol belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Simple Service Discovery Protocol to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Simple Service Discovery Protocol from memory before moving on to harder problems.

Reference excerpt

The Simple Service Discovery Protocol (SSDP) is a network protocol, associated with the Internet protocol suite, for advertisement and discovery of network services and presence information. It accomplishes this without the assistance of server-based configuration mechanisms, such as Dynamic Host Configuration Protocol (DHCP) or the Domain Name System (DNS), and without special static configuration of a network host. SSDP is the basis of the discovery protocol of Universal Plug and Play (UPnP) and is intended for use in residential or small office environments. It was formally described in an IETF Internet Draft by Microsoft and Hewlett-Packard in 1999. Although the IETF proposal has since expired (April, 2000), SSDP was incorporated into the UPnP protocol stack, and a description of the final implementation is included in UPnP standards documents.

Protocol transport and addressing SSDP is a text-based protocol based on HTTPU, which uses UDP as the underlying transport protocol. Services are announced by the hosting system with multicast addressing to a specifically designated IP multicast address at UDP port number 1900. In IPv4, the multicast address is 239.255.255.250 and SSDP over IPv6 uses the address set ff0x::c for all scope ranges indicated by x. This results in the following well-known practical multicast addresses for SSDP:

239.255.255.250 (IPv4 site-local address) ff02::c (IPv6 link-local) ff05::c (IPv6 site-local) Additionally, applications may use the source-specific multicast addresses derived from the local IPv6 routing prefix, with group ID c (decimal 12). SSDP uses the HTTP method NOTIFY to announce the establishment or withdrawal of services (presence) information to the multicast group. A client that wishes to discover available services on a network uses method M-SEARCH. Responses to such search requests are sent via unicast addressing to the originating address and port number of the multicast request. Microsoft's IPv6 SSDP implementations in Windows Media Player and Server use the link-local scope address. Microsoft uses port number 2869 for event notification and event subscriptions. However, early implementations of SSDP also used port 5000 for this service.

DDoS attack In 2014 it was discovered that SSDP was being used in DDoS attacks known as an SSDP reflection attack with amplification. Many devices, including some residential routers, have a vulnerability in the UPnP software that allows an attacker to get replies from port number 1900 to a destination address of their choice. With a botnet of thousands of devices, the attackers can generate sufficient packet rates and occupy bandwidth to saturate links, causing the denial of services. The network company Cloudflare has described this attack as the "Stupidly Simple DDoS Protocol".

Firefox vulnerability Firefox for Android prior to version 79 did not properly validate the schema of the URL received in SSDP and were vulnerable to remote code execution. An attacker on the same network could create a malicious server pretending to be a device supporting casting, but instead of a configuration file it would return an intent:// URL. Firefox would launch the intent (if it was supported by the device) and thus would execute arbitrary code. This is not a bug with SSDP, just an improper validation performed by Firefox casting service.

See also Discovery and Launch Jini Multicast DNS (mDNS) Neighbor Discovery Protocol (NDP) Service Location Protocol WS-Discovery Zero-configuration networking

References

Worked examples

Example 1 — a first encounter with Simple Service Discovery Protocol

Start with the simplest possible case. Write down what Simple Service Discovery Protocol claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Simple Service Discovery Protocol before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Simple Service Discovery Protocol ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Simple Service Discovery Protocol

In research: Simple Service Discovery Protocol appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Simple Service Discovery Protocol in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Simple Service Discovery Protocol is common in secondary-school and first-year university syllabi. It links to neighbouring topics Application layer protocols, Service discovery protocols, Windows communication and services, so understanding it makes those chapters shorter.
In everyday life: Look for Simple Service Discovery Protocol outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Simple Service Discovery Protocol in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Simple Service Discovery Protocol means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Simple Service Discovery Protocol out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Simple Service Discovery Protocol in simple terms?

Why does Simple Service Discovery Protocol matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Simple Service Discovery Protocol?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Simple Service Discovery Protocol.