Peer Name Resolution Protocol (PNRP) is a

peer-to-peer Peer-to-peer (P2P) computing or networking is a distributed application architecture that partitions tasks or workloads between peers. Peers are equally privileged, equipotent participants in the network, forming a peer-to-peer network of Node ...

protocol designed by

Microsoft Microsoft Corporation is an American multinational corporation and technology company, technology conglomerate headquartered in Redmond, Washington. Founded in 1975, the company became influential in the History of personal computers#The ear ...

. PNRP enables dynamic name publication and resolution, and requires

IPv6 Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communication protocol, communications protocol that provides an identification and location system for computers on networks and routes traffic ...

. PNRP was first mentioned during a presentation at a P2P conference in November 2001. It appeared in July 2003 in the Advanced Networking Pack for Windows XP, and was later included in the Service Pack 2 for Windows XP. PNRP 2.0 was introduced with

Windows Vista Windows Vista is a major release of the Windows NT operating system developed by Microsoft. It was the direct successor to Windows XP, released five years earlier, which was then the longest time span between successive releases of Microsoft W ...

and was available for download for Windows XP Service Pack 2 users. PNRP 2.1 is included in

SP1,

Windows Server 2008 Windows Server 2008, codenamed "Longhorn Server" (alternatives: "Windows Vista Server" or "Windows Server Vista"), is the seventh major version of the Windows NT operating system produced by Microsoft to be released under the Windows Server b ...

and

Windows XP Windows XP is a major release of Microsoft's Windows NT operating system. It was released to manufacturing on August 24, 2001, and later to retail on October 25, 2001. It is a direct successor to Windows 2000 for high-end and business users a ...

SP3. PNRP v2 is not available for

Windows XP Professional x64 Edition Windows XP Professional x64 Edition is an edition of Microsoft's Windows XP operating system that supports the x86-64 architecture. It was released on April 25, 2005, alongside the x86-64 versions of Windows Server 2003. Windows XP Profession ...

or any edition of

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Windows Remote Assistance Quick Assist is a Microsoft Windows feature that allows a user to view or control a remote Windows computer over a network or the Internet to resolve issues without directly touching the unit. It is based on the Remote Desktop Protocol (RDP). It ...

Windows 7 Windows 7 is a major release of the Windows NT operating system developed by Microsoft. It was Software release life cycle#Release to manufacturing (RTM), released to manufacturing on July 22, 2009, and became generally available on October 22, ...

uses PNRP, Teredo and IPv6 when connecting using the ''Easy Connect'' option. The design of PNRP is covered by US Patent #7,065,587, issued on June 20, 2006. Support for PNRP was removed in

Windows 10 Windows 10 is a major release of Microsoft's Windows NT operating system. The successor to Windows 8.1, it was Software release cycle#Release to manufacturing (RTM), released to manufacturing on July 15, 2015, and later to retail on July 2 ...

with version 1909.

PNRP services

The PNRP is a distributed name resolution protocol allowing Internet hosts to publish "peer names" and corresponding IPv6 addresses and optionally other information. Other hosts can then resolve the peer name, retrieve the corresponding addresses and other information, and establish peer-to-peer connections. With PNRP, peer names are composed of an "authority" and a "qualifier". The authority is identified by a secure hash of an associated

public key Public-key cryptography, or asymmetric cryptography, is the field of cryptographic systems that use pairs of related keys. Each key pair consists of a public key and a corresponding private key. Key pairs are generated with cryptographic alg ...

, or by a place-holder (the number zero) if the peer name is "unsecured". The qualifier is a

string String or strings may refer to: *String (structure), a long flexible structure made from threads twisted together, which is used to tie, bind, or hang other objects Arts, entertainment, and media Films * ''Strings'' (1991 film), a Canadian anim ...

, allowing an authority to have different peer names for different services.Peer Name Resolution Protocol
/ref> If a peer name is secure, the PNRP name records are signed by the publishing authority, and can be verified using its public key. Unsecured peer names can be published by anybody, without possible verification. Multiple entities can publish the same peer name. For example, if a peer name is associated with a group, any group member can publish addresses for the peer name. Peer names are published and resolved within a specified scope. The scope can be a local link, a site (e.g. a campus), or the whole Internet.

PNRP and Distributed Hash Tables

Internally, PNRP uses an architecture similar to

distributed hash table A distributed hash table (DHT) is a Distributed computing, distributed system that provides a lookup service similar to a hash table. Key–value pairs are stored in a DHT, and any participating node (networking), node can efficiently retrieve the ...

systems such as Chord or

Pastry Pastry refers to a variety of Dough, doughs (often enriched with fat or eggs), as well as the sweet and savoury Baking, baked goods made from them. The dough may be accordingly called pastry dough for clarity. Sweetened pastries are often descr ...

. The peer name is hashed to produce a

128-bit General home computing and gaming utility emerged at 8-bit word sizes, as 28=256 Word (computer architecture), words, a natural unit of data, became possible. Early 8-bit CPUs (such as the Zilog Z80 and MOS Technology 6502, used in the 1977 Co ...

peer identifier, and a DHT-like algorithm is used to retrieve the location of the host publishing that identifier. There are however some significant differences. DHT systems like Chord or Pastry store the indices of objects (hashes) at the node whose identifier is closest to the hash, and the routing algorithm is designed to find that node. In contrast, PNRP always store the hash on the node that publishes the identifier. A node will thus have as many entries in the routing system as the number of identifiers that it publishes. The PNRP design arguably trades increased security and robustness for higher routing cost. Most DHT systems assume that only one node publishes a specific index. In contrast, PNRP allows multiple hosts to publish the same name. The internal index is in fact composed of the 128-bit hash of the peer name and a 128-bit location identifier, derived from an IPv6 address of the node. PNRP does not use a routing table, but rather a cache of PNRP entries. New cache entries are acquired as a side effect of ongoing traffic. The cache maintenance algorithm ensures that each node maintains adequate knowledge of the "cloud". It is designed to ensure that the time to resolve a request varies as the logarithm of the size of the cloud.

References

External links

Microsoft Peer-to-Peer Networking blog on how Windows features use PNRP

PNRPv2 protocol specification
at MSDN
Microsoft PNRP documentation (API)
at MSDN
MSDN-Article by Justin Smith, featuring PNRP

Windows Peer-to-Peer Networking
at Microsoft TechNet
Advanced Networking Pack for Windows XP
at Microsoft.com
Distributed Peer-to-peer Name Resolution
Slide deck presented by Christian Huitema at the O'Reilly P2P conference in November 2001. * , , , , , , {{US patent, 7496648 Windows Vista Network protocols

PNRP services

PNRP and Distributed Hash Tables

See also

References

External links