GNU Gatekeeper (abbreviated as GnuGk) is a

free software Free software or libre software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any adapted versions. Free software is a matter of liberty, ...

project that implements an

H.323 Gatekeeper An H.323 Gatekeeper serves the purpose of Call Admission Control and translation services from E.164 IDs (commonly a phone number) to IP addresses in an H.323 telephony network. Gatekeepers can be combined with a gateway function to proxy H.323 c ...

based on the

OpenH323 The OpenH323 project had as its goal the development of a full featured, open source ( MPL) implementation of the H.323 Voice over IP protocol. The code was written in C++ and, through the development effort of numerous people around the world, sup ...

or H323Plus stack. A gatekeeper provides address translation, admissions control, call routing, authorization and accounting services to an

H.323 H.323 is a recommendation from the ITU Telecommunication Standardization Sector (ITU-T) that defines the protocols to provide audio-visual communication sessions on any packet network. The H.323 standard addresses call signaling and control, m ...

system defined on the H.323 standard by

ITU-T The ITU Telecommunication Standardization Sector (ITU-T) is one of the three sectors (divisions or units) of the International Telecommunication Union (ITU). It is responsible for coordinating standards for telecommunications and Information Commu ...

Features

GnuGk's set of features include: * Created for

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which i ...

Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ...

macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac (computer), Mac computers. Within the market of ...

, Solaris,

FreeBSD FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular ...

OpenBSD OpenBSD is a security-focused operating system, security-focused, free and open-source, Unix-like operating system based on the Berkeley Software Distribution (BSD). Theo de Raadt created OpenBSD in 1995 by fork (software development), forking N ...

and

NetBSD NetBSD is a free and open-source Unix operating system based on the Berkeley Software Distribution (BSD). It was the first open-source BSD descendant officially released after 386BSD was forked. It continues to be actively developed and is a ...

* A

policy Policy is a deliberate system of guidelines to guide decisions and achieve rational outcomes. A policy is a statement of intent and is implemented as a procedure or protocol. Policies are generally adopted by a governance body within an orga ...

-based flexible

routing Routing is the process of selecting a path for traffic in a network or between or across multiple networks. Broadly, routing is performed in many types of networks, including circuit-switched networks, such as the public switched telephone netw ...

mechanism * Calling and called numbers rewriting, including CLI rewriting * Full H.323 proxy, including

Real-time Transport Protocol The Real-time Transport Protocol (RTP) is a network protocol for delivering audio and video over IP networks. RTP is used in communication and entertainment systems that involve streaming media, such as telephony, video teleconference applicati ...

(RTP) and RTP Control Protocol (RTCP) media channels, and T.120 data channels *

NAT traversal Network address translation traversal is a computer networking technique of establishing and maintaining Internet protocol connections across gateways that implement network address translation (NAT). NAT traversal techniques are required for m ...

using a number of protocols, including H.460.17, H.460.18 and H.460.19 *

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

support (incl. IPv4-IPv6 proxying) *

LDAP The Lightweight Directory Access Protocol (LDAP ) is an open, vendor-neutral, industry standard application protocol for accessing and maintaining distributed directory information services over an Internet Protocol (IP) network. Directory serv ...

directory support (H.350) * Call retry-failover * Clustering support by neighbors, parent-child, alternates GK *

Transmission Control Protocol The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, the entire suite is common ...

(TCP) status port for monitoring and external call routing *

H.235 H.235 covers security and encryption for H.323 and other H.245 based terminals. The standard addresses authentication by means of several algorithms, including Diffie-Hellman methods, and privacy. Privacy allows for encryption, also of the me ...

security * Accounting and call authorization via SQL database,

RADIUS In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...

ENUM Telephone number mapping is a system of unifying the international telephone number system of the public switched telephone network with the Internet addressing and identification name spaces. Internationally, telephone numbers are systematicall ...

support

License

It is covered by the GPL-2.0-only license. Besides, the authors explicitly grant the right to link it to the OpenH323 and

OpenSSL OpenSSL is a software library for applications that provide secure communications over computer networks against eavesdropping or need to identify the party at the other end. It is widely used by Internet servers, including the majority of HT ...

libraries. This is necessary, since GNU GPL is incompatible with the licenses of these libraries.

History

Originally, a proof-of-concept gatekeeper was developed by Xianping Chen, Joe Metzger and Rajat Todi for an experiment. At the start of 1999, Jan Willamowius convinced the first authors to license their code under GNU GPL and began the project. The code was named ''OpenH323 Gatekeeper'', short ''OpenH323GK''. A team at mediaWays provided

subsystem and overlapped sending. In 2000, there are tens of people contributed to the project for coding and testing. At the start of 2001,

Chih-Wei Huang Chih-Wei Huang ( 黃志偉) is a developer and promoter of free software who lives in Taiwan. He is famous for his work in the VoIP and internationalization and localization fields in Greater China. The user name he usually uses is cwhuang. Pr ...

at Citron and his team began to use and modify the project for their VoIP services. In September 2001 Openh323GK version 1.0 was released. In 2002, GnuGk 2.0 was released. It had new architecture for gatekeeper routed mode which can handle thousands of concurrent calls, and introduced full H.323 proxy and Citron's NAT technology. These features made it a carrier-graded H.323 gatekeeper suitable for commercial operations. To avoid confusion with other OpenH323 based gatekeepers, the project was renamed ''GNU Gatekeeper'', short ''GnuGk'', to reflect that it was the only gatekeeper available under a GNU license. In 2004, version 2.2 was released with a redesigned architecture, followed by the more stable version 2.2.1 in 2005.GnuGk Paper at Fostel 2004
/ref> In 2006, version 2.2.4 introduced call failover, ENUM and CLI rewriting.GnuGk Paper at Fostel 2006
/ref> In 2012, version 3.0 added IPv6 and full H.460.18/H.460.19 traversal zone support.
/ref>

Compatibility

The official website maintains an interoperability list for H.323 software and products.
/ref>

Contributors

Jan Willamowius is the project founder and still the maintainer . Over the years dozens of people contributed code and bug fixes. Among the most active were the team a Mediaways (LDAP), Michal Zygmuntowicz (radius support), Chih-Wei Huang (2.2 redesign), and Simon Horne (NAT features).

References

External links

*{{official website
BlogGerman site
a

Graphical User Interface The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows User (computing), users to Human–computer interaction, interact with electronic devices through graphical icon (comp ...

(GUI) for the GNU Gatekeeper
GnuGk ACD
an

automatic call distributor An automated call distribution system, commonly known as automatic call distributor (ACD), is a telephony device that answers and distributes incoming calls to a specific group of terminals or agents within an organization. ACDs direct calls based ...

(ACD) for the GNU Gatekeeper Free VoIP software Free communication software Free server software Free software programmed in C++ Cross-platform free software Network address translation Videotelephony