Book Description It used to be that two laptops, sitting side by side, couldn't communicate with each other; they may as well have been a thousand miles apart. But that was then, before the advent of Zero Configuration Networking technology. This amazing cross-platform open source technology automatically connects electronic devices on a network, allowing them to interoperate seamlessly-without any user configuration. So now you don't have to lift a finger! Needless to say, it has completely changed the way people connect to devices and programs for printing, file sharing, and other activities. Zero Configuration Networking: The Definitive Guide walks you through this groundbreaking network technology, with a complete description of the protocols and ways to implement network-aware applications and devices. Written by two Zero Configuration Networking experts, including one of Apple's own computer scientists, the book covers more than just file sharing and printing.
Zero Configuration Networking also enables activities such as music and photo sharing and automatic buddy discovery on Instant Messaging applications. In fact, Zero Configuration Networking can be used for virtually any device that can be controlled by a computer. And this handy guide has the inside scoop on all of its capabilities-and how you can easily apply them in your own environment. For the technically advanced, Zero Configuration Networking: The Definitive Guide examines the three core technologies that make up Zero Configuration Networking: Link-Local Addressing, Multicast DNS, and DNS Service Discovery. It also reviews a series of APIs, including C-API, Java API, CFNetServices, and Cocoa's NSNetServices.
Whether you want to understand how iTunes works, or you want to network a series of laptops and other devices at your office for maximum efficiency, you'll find all the answers in this authoritative guide.
Zero configuration networking may sound like an oxymoron to many who spend most of their time setting up and mending networks. But don't decide on a career change yet—although zero configuration networks exist and work, they don't work always and everywhere. In this article I describe the current state of the affairs in zero configuration IP networking, introduce Zeroconf, the suite of zero configuration IP protocols, and tell what they do and how they work. This article is only a brief introduction to zero configuration networking and Zeroconf, so if you are really interested in all the details, refer to the sources listed in the References section at the end of this article. These and other requirements are defined in an Internet Draft titled 'Requirements for Automatic Configuration of IP Hosts' by Aidan Williams 2.
This document does not define Zeroconf protocols themselves but instead spells out the requirements that should be met to achieve effective and useful zero configuration IP networking. One of the most important requirements for any Zeroconf protocol is that it should not interfere with other protocols and it must be able to exist on the same network with other non-Zeroconf protocols and devices. Another requirement is 'no less' security— Zeroconf protocols should not be less secure than existing non-Zeroconf protocols—more on this later.
Although IPv6 addresses some of the requirements of zero configuration networking (such as automatic allocation of link-local addresses), other requirements have yet to be met for both IPv4 and IPv6. Link-local addressing and naming are meaningful only in a particular network; link-local addresses and names are not global and are not unique globally. In this case it means that Zeroconf is intended for use in small wired or wireless local-area networks in situations and places where zero configuration is necessary. It is appropriate to use Zeroconf in such networks when there is no possibility (or it is inappropriate) to set up a working IP network using the traditional technologies such as DNS and DHCP. Zeroconf is not appropriate and should not be used in many cases, for example in. Likewise, Zeroconf advantages from one viewpoint may become annoying problems from another.
Consider, for instance, the automatic distribution and configuration of link-local IP addresses. For a home network user this is a blessing—no longer do you have to spend time creating an addressing scheme and setting the IP addresses and netmasks on devices that should just work. But for an enterprise network (especially an incorrectly configured one), sudden appearance of nodes with (yet) unfamiliar and strange (this is not your regular. 'Zeroconf protocols are intended to operate in a local scope, in networks containing one or more IP subnets, and potentially in parallel with standard configured network protocols. Application protocols running on networks employing zeroconf protocols will be subject to the same sets of security issues identified for standard configured networks. Examples are: denial of service due to the unauthenticated nature of IPv4 ARP and lack of confidentiality unless IPSec-ESP, TLS, or similar is used.
However, networks employing zeroconf protocols do have different security characteristics, and the subsequent sections attempt to draw out some of the implications. Security schemes usually rely on some sort of configuration. Security mechanisms for zeroconf network protocols should be designed in keeping with the spirit of zeroconf, thus making it easy for the user to exchange keys, set policy, etc. It is preferable that a single security mechanism be employed that will allow simple configuration of all the various security parameters that may be required.
Generally speaking, security mechanisms in IETF protocols are mandatory to implement. A particular implementation might permit a network administrator to turn off a particular security mechanism operationally. However, implementations should be 'secure out of the box' and have a safe default configuration. Zeroconf protocols MUST NOT be any less secure than related current IETF-Standard protocols. This consideration overrides the goal of allowing systems to obtain configuration automatically. Security threats to be considered iclude both active attacks (e.g. Denial of service) and passive attacks (e.g.
Protocols that require confidentiality and/or integrity should include integrated confidentiality and/or integrity mechanisms or should specify the use of existing standards-track security mechanisms (e.g. TLS (RFC 2246), ESP (RFC 1827), AH (RFC 2402) appropriate to the threat.' However, neither of these is possible in zero configuration networks. Therefore, an automatic mechanism for dynamic configuration of IP addresses without any manual intervention or dependence on third-party service (that is, DHCP) is necessary.
![Zero configuration networking Zero configuration networking](/uploads/1/2/4/0/124018144/993092260.jpg)
This mechanism already exists in IPv6 but not in IPv4. In 'Dynamic Configuration of IPv4 Link-Local Addresses' 3, Stuart Cheshire, Bernard Aboba, and Erik Guttman describe a method that may be used in IPv4 networks to automatically assign IPv4 addresses valid for local communication on a particular interface. A special network. Address conflicts in IP networks are annoying problems that (needlessly) take time and effort to detect and rectify, so a separate document on address conflict detection was deemed necessary. 'IPv4 Address Conflict Detection' 4 by Stuart Cheshire presents two things: first, a way to prevent this unfortunate situation of conflicting IP addresses from happening, and second, a way to detect address conflicts if they do happen even after all the precautions. Both of these are accomplished using the. 'The ARP protocol RFC 826 is insecure.
A malicious host may send fraudulent ARP packets on the network, interfering with the correct operation of other hosts. For example, it is easy for a host to answer all ARP requests with responses giving its own hardware address, thereby claiming ownership of every address on the network. This specification makes this existing ARP vulnerability no worse, and in some ways makes it better: Instead of failing silently with no indication why, hosts implementing this specification are required to either attempt to reconfigure automatically, or if not that, at least inform the human user of what is happening.' 'Performing DNS queries via IP Multicast' 6 by Stuart Cheshire suggests some very useful ideas on how to use mDNS with maximum benefit and minimum hassle in zero configuration networks. In my opinion, the best thing about this proposal is that it does not require any changes to the DNS protocol (messages, resource record types, etc.) itself. Instead it concentrates on the use of multicast for name resolution in environments where no DNS servers exist (and where one would not reasonably expect them to). The goal is to have a working name resolution service without name servers.
The document proposes to use. With computers and computer networks becoming more and more complex and sophisticated, some people (including the author of this article) believe that care should be taken by those in the know not to create more problems than we solve using these computers and networks. Yes, we want more features—but we also need to remember that most users of these features do not have doctorates in computer science and (surprise, surprise) don't even wish to. Zero configuration networking would probably help in this regard, minimizing and even eliminating in some cases the need to configure and administer small networks. Let me conclude by quoting once more from the Zeroconf Working Group.
Chapter 1. Introduction to Bonjour and Zeroconf You walk in a few minutes late to a meeting and want to know what you’ve missed. You open your text editor and your computer automatically discovers a shared document in which one or more attendees are taking notes. You have a couple of colleagues who are busy in another meeting but are interested in the topics being discussed in your meeting. You invite your colleagues to view the notes being taken and to contribute their comments and questions. A presenter announces that anyone wanting a copy of his slides should let him know.
You open your local Instant Messenger application and see his name in the list of available names, even though you have never met before and he is not in your buddy list. A moment later, he has placed his presentation in your drop box in your Public folder, which he has discovered in his network directory. The meeting comes to an end. Before anyone erases the whiteboard, someone snaps a quick picture or two and puts it in their photo-sharing library so that anyone interested can download it.
You notice a new entry in your audio software that announces that the person who was recording the session has already posted it in her shared audio library. Before you save the notes on the session, you decide to print out a copy to read on the plane ride back.
Computer Networking Pdf Notes
In the print dialog, you discover several printers and choose the one labeled “Third Floor Meeting Rooms.” This is not a fantastical glimpse of the elusive future. It is a concrete description of what is available today using Zeroconf. In this chapter, you will get a quick overview of the various components that make up Zeroconf. In the following four chapters, these details will be fleshed out.
The second half of this chapter examines the Zeroconf design principles that build on two decades of experience with the AppleTalk Name Binding Protocol. Zeroconf’s Many Names The seeds of Zeroconf were planted in some postings by Stuart Cheshire on the Net-Thinkers mailing list in 1997. This led to the IETF holding two “Birds of a Feather” (BOF) sessions at the March and July 1999 IETF meetings on the subject of “Networking in the Small” (NITS), co-chaired by Stuart Cheshire and Peter Ford. Out of the NITS BOF meetings, the Zero Configuration Networking (Zeroconf) Working Group was formed in September 1999. In May 2002, Apple announced its trademark “Rendezvous” for the Zeroconf technologies, a little like the way Apple uses its trademark “AirPort” for IEEE 802.11 wireless networking. Unfortunately for Apple, another company also had a networking product by the name of “Rendezvous,” and in April 2005, Apple announced the new Apple name for the Zeroconf technologies: “Bonjour.” Other third-party products can also carry the Bonjour name and logo. Apple doesn’t charge any money to license the name and logo; the products just have to pass Apple’s Bonjour Conformance Test to verify that they do in fact implement the specifications properly.
Meanwhile, other open source implementations of the Zeroconf technologies have also been created, including Howl and Avahi. The terms “Bonjour” and “Zeroconf” are often used interchangeably, but as a general rule, this book uses the term “Zeroconf” when referring to the technology in general and “Bonjour” when referring to it in an Apple-specific context.
For example, iChat on Mac OS X doesn’t have a “Zeroconf” window; it has a “Bonjour” window (it says “Bonjour” at the top of the window). Rare person who takes the time to say, “Now that I have an IP address, I could use a friendly domain name. I should learn how to set up DNS on my laptop.” A typical user of Zeroconf should not be aware of the infrastructure required.
She just wants to use a printer, stream music, exchange photos, or use some other service. The architecture of Zeroconf is built around simplicity. It should be as easy for an end user to connect to a printer or locate streamed music as it is for him to turn on a light bulb. The simplicity extends to implementers as well. A vendor of an inexpensive device who desires to use Zeroconf should not find it hard to implement Zeroconf, even in devices with extremely limited memory capacity. Browse for services With Zeroconf, you browse for services, not for hardware.
The reason for this is simple but important: if you want to print, there is little benefit to discovering hardware that doesn’t do printing. Similarly, there is little benefit to discovering things that are printers but speak only a printing protocol that your client does not support, since you wouldn’t be able to use those printers. Conversely, suppose that there is a device on the network in a legal office that functions, protocol-wise, as a printer, but instead of printing on paper, it archives documents as date-stamped PDF files on recordable CDs. You would want your printing client to discover this service, since it’s a service your printing client can use.
Suppose there were an inexpensive USB printer (which doesn’t have Postscript or networking) connected to a desktop computer (which does), with software making Postscript printing service available to other machines on the network via IPP (Internet Printing Protocol). You would want your Postscript IPP printing client to discover this service, since it’s a service you can use. What is it that your printing client is discovering, in this case? The USB printer? The desktop computer? The software? The insight here is to realize that what your printing client is discovering is the aggregate service offered by the computer, the printer, and the software working in concert, and it is that aggregate service that is being advertised as a logical entity on the network in its own right.
The USB printer could break and be replaced, and the logical service being offered would remain the same. The desktop computer could break and be replaced, and the logical service being offered would remain the same. Even the software could be upgraded or replaced, while the logical Postscript IPP printing service being offered to network clients would remain unchanged. The important principle here is that when you’re looking for services on the network, the relevant question is not “What are you?” or even “What do you do?” but “Do you speak my language?”. Available services The list that the user gets should be services that are currently available to them. They should be able to see the list of currently available printers, select one, and use it. As with all such network protocol designs, there is a trade-off between timeliness of information and network efficiency.
The particular to hand held story thrusts you into an ongoing turf warfare. Nfs carbon game free download for android mobile. Team contributors improve with race experience and also you’ll must pick out either to develop every team member over the route of the game or switch them out while warm new recruits come available. Need for Speed Carbon Own the City psp iso apk android for ppsspp free download working on mobile and pc,Want for speed Carbon personal the city functions all-new team-based totally gameplay and an unique east coast open-world town to discover. The way you select and control your group can be the distinction among victory and defeat. You are challenged to build an unstoppable crew, win races against fierce rivals, and outwit the cops.
Continuously querying the network to find what services are available gives accurate, up-to-date information but can impose an unreasonable burden on the network. Querying the network just once is much more efficient, but the client’s information soon gets out of date, necessitating a “refresh” button in the UI, which then puts the burden on the human user to keep clicking the refresh button (which puts a burden on the network). Zeroconf solves these problems using a variety of techniques. For efficiency, clients query the network infrequently, as little as once per hour.
To avoid long delays before new services are discovered, when a service starts up it sends a few multicast announcement packets, so clients become aware of the new service even before performing their next scheduled query. IP Multicast addresses are special destination addresses that cause packets to be delivered to all interested parties on the local network, rather than just to a single machine. When services go away, they send multicast “goodbye” packets, so they are promptly removed from all clients’ UI lists. In the event that a service is unceremoniously disconnected without getting a chance to send its “goodbye” packet, stale data may remain in lists for a while, but even this case is handled by Zeroconf. When a client attempts to contact a stale service that is no longer present, the failure is noted, and the service is promptly removed from the list of available services. This prompt removal occurs not only on the client that directly experienced the failure but also on all the other clients on the same network link, which passively observe the failure and update their own lists too. Zeroconf uses these and a variety of other techniques to provide timely, accurate information while keeping the network traffic to a minimum.
This kind of peer-to-peer, multicast-based protocol is great for small networks because it is very reliable and requires no dedicated service-discovery infrastructure, but no matter how efficient the protocol, there will come a network size where it no longer makes sense. In an organization with thousands of machines, having every single machine multicasting to every other machine all the time would not be reasonable. Beyond a certain size, every service-discovery protocol has to transition from using peer-to-peer multicast to some kind of centralized repository to hold service information. Services and clients communicate with the centralized repository using a wide-area protocol.
Zero Configuration Networking Youtube
In Zeroconf, the centralized repository is one that most companies already have—a DNS server—and the wide-area protocol is the standard DNS protocol with two small extensions, Update Leases and Long-Lived Queries. Update Leases allow a DNS server to expire server records if the service that created them crashes, and Long-Lived Queries allow a client to be notified as services come and go, rather than having to keep polling the server to find out what’s new.
Easy browsing Zeroconf would never have been so widely adopted if using it required popping open a terminal window and typing in obscure commands. Command-line tools are great for developers and network administrators, but end users will be browsing for services within a context. They are not conscious that they are requesting a list of services that implement a protocol. For example, when running iTunes, users simply see a list called “Shared Music.” They don’t need to be aware that iTunes is performing a query for Zeroconf service type daap.tcp to find the list of local servers offering the Digital Audio Access Protocol (DAAP) service. Another thing you’ll notice is that the names of shared music sources displayed in iTunes don’t need to look like ',” all lowercase with no spaces or other punctuation.
In the example at the beginning of this chapter, the printer was named “Third Floor Meeting Rooms,” not '.” In command-line user interfaces, you want names to be short and quick to type. In graphical user interfaces, you don’t need to type names because you just select them from a list of choices, so they can be long and descriptive and can contain rich punctuation, accented letters, and non-roman characters, such as Kanji. Claiming an IP address The first requirement for IP networking is an IP address. There are existing mechanisms for IPv4 address allocation, such as using manual configuration or a DHCP server, but when neither of these is available, Zeroconf-capable devices will use a self-assigned IPv4 link-local address instead.
In brief, the mechanism behind self-assigned addresses is that the device selects an address at random within a prescribed range, sends some ARP requests, and then, if no answers are received, proceeds to use that address. Self-assigned IPv4 link-local addresses are discussed in detail in. IPv6 also has self-assigned link-local addresses, though sadly, at the present time—even though Mac OS X, Windows, and Linux all support IPv6—most of the low-cost peripherals that they talk to, such as printers and cameras, don’t yet support IPv6.
Claiming a name The second requirement is that the typical usage model for IP networking expects hosts to have names, not just numerical addresses. Having to remember and type numerical addresses is cumbersome at best, and when the addresses are being picked randomly, it may not even be possible. We need a way to associate a stable name with each device, in order to determine what address it has picked for itself, at this instant. The Internet’s existing mechanism for associating names with addresses is a DNS server, but when no DNS server is available, Zeroconf-capable devices will use Multicast DNS (mDNS) to achieve substantially the same effect on the local link, without having to set up and maintain a dedicated DNS server. In brief, the mechanism behind mDNS names is very similar to self-assigned addresses: the device sends a few mDNS queries for its desired name, and if no answers are received, the device can then use that name.
Multicast DNS naming is discussed in detail in. With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.
This article may require to meet Wikipedia's. No has been specified. Please help if you can.
(December 2010) Zero-configuration networking ( zeroconf) is a set of technologies that automatically creates a usable based on the (TCP/IP) when computers or network peripherals are interconnected. It does not require manual operator intervention or special configuration servers. Without zeroconf, a network administrator must set up, such as (DHCP) and (DNS), or configure each computer's network settings manually. Zeroconf is built on three core technologies: automatic assignment of numeric for networked devices, automatic distribution and resolution of computer, and automatic, such as printing devices.
'Apipa', Microsoft. 'How to use automatic TCP/IP addressing without a DHCP server', Microsoft. ^ Marshall Brain and Stephanie Crawford, howstuffworks.
^. Microsoft Knowledge Base.
Retrieved 1 November 2015. Manning, (draft), Water springs.
(webpage), Microsoft. (webpage), Apple. (webpage), Google. (electronic mail message), IETF. (electronic mail message), IETF.
(electronic mail message), IETF. (electronic mail message), IETF. Windows Dev Center. Retrieved 1 November 2015., (rant). Retrieved 23 October 2015.
Windows Dev Center. Retrieved 1 November 2015., DNS-SD., IETF., IETF., IETF. (World Wide Web log), GNU citizen., Mac Dev Center, 2004-08-31. 'Bonjour for MS Windows 1.0.4', Apple. Lennart,: 0 pointer., Source forge. 'Stable box', Google.,: UTS.
![Notes Notes](/uploads/1/2/4/0/124018144/938864242.jpg)
(C source code), Zero conf. 'Zeroconf in udhcpc', (electronic mail message), Busy box, May 2005.
Marples, Roy, (wiki) (project). 'Link-Local ARP Measurements', (wiki),: UVA Sources. Guttman, Erik (2001), 'Autoconfiguration for IP Networking: Enabling Local Communication', IEEE Internet Computing, 5 (3): 81–86,: External links., Source forge, a pure Java implementation of mDNS/DNS-SD., Source forge, a pure implementation of mDNS/DNS-SD., Mono project, a cross platform (Linux, MS Windows, Apple Mac), unified Mono/.NET library for Zeroconf, supporting both Bonjour and Avahi., Source forge, a cross-platform wxWidgets-based service discovery module without external dependencies. Cheshire, Stuart, (draft), Multicast DNS. ———, (draft), DNS‐SD.
———, (video) (tech talk), Google. ———, including Internet drafts., DNS based Service Discovery. Johns, Heath (December 2002), (article), O'Reilly, slightly outdated.
Computer Networking Notes In Pdf
'Zeroconf Technologies', (wiki), NL: UVA. (charter), which coordinates LLMNR standardization.
Steinberg, Daniel; Cheshire, Stuart, O'Reilly.