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Antennas for High-speed Amateur-radio Multimedia Network (HamNET) in Europe, part of the AMPRNet wireless mesh network

The AMPRNet (AMateur Packet Radio Network) or Network 44 is used in amateur radio for packet radio and digital communications between computer networks managed by amateur radio operators. Like other amateur radio frequency allocations, an IP range of 44.0.0.0/8 was provided in 1981 for Amateur Radio Digital Communications (a generic term) and self-administered by radio amateurs. In 2001, undocumented and dual-use of 44.0.0.0/8 as a network telescope began,[1] recording the spread of the Code Red II worm in July 2001. In mid-2019, part of IPv4 range was sold off for conventional use, due to IPv4 address exhaustion.

Protocol

[edit]

Beginning on 1 May 1978, the Canadian authorities allowed radio amateurs on the 1.25-meter band (220 MHz) to use packet radio, and later in 1978 announced the "Amateur Digital Radio Operator's Certificate".[2][3] Discussion on digital communication amateur radio modes, using the Internet protocol suite[4] and 44/8 IPv4 addresses followed subsequently.

By 1988, one thousand assignments of address space had been made.[5] As of December 2009 approximately 1% of inbound traffic volume to the 44/8 network was legitimate radio amateur traffic that could be routed onwards, with the remaining 2‒100 gigabyte per day of Internet background noise being diverted and logged by the University of California San Diego (UCSD) internet telescope for research purposes.[1] By 2016, the European-based High-speed Amateur-radio Multimedia NETwork (HAMNET) offered a multi-megabit Internet Protocol network with 4,000 nodes, covering central Europe.[6]

History and design

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The use of the Internet protocols TCP/IP on amateur (ham) radio occurred early in Internet history, preceding the public Internet by over a decade. In 1981, Hank Magnuski obtained the class A 44/8 netblock of 16.7 million IP addresses for amateur radio users worldwide.[7][8] This was prior to Internet flag day (1 January 1983) when the ARPANET Network Control Protocol (NCP) was replaced by the Transmission Control Protocol (TCP).[8] The initial name used by Jon Postel in RFC 790 was the "Amateur Radio Experiment Net".[7]

Originally the amateur link layer protocol AX.25 carried several competing higher level protocols, with TCP/IP a minority due to the complexity of the configuration and the high protocol overhead. Very few systems operated over HF for this reason. One approach for 1,200/9,600-baud VHF/UHF operation emerged as TCP/IP over ROSE (Radio Amateur Telecommunications Society "RATS" Open Systems Environment, based on X.25 CCITT standard). Within just a few years the public Internet made these solutions obsolete. The ROSE system today is maintained by the Open Source FPAC Linux project.[9]

The AMPRNet is connected by wireless links and Internet tunnels. Due to the bandwidth limitations of the radio spectrum, 300 bit/s is normally used on HF, while VHF and UHF links are usually 1,200 bit/s to 9,600 bit/s. Mass-produced Wi-Fi access points equipment on 2.4 GHz and 5 GHz is now being used on nearby amateur frequencies to provide much faster links as HSMM or hinternet. Since it is based on IP, the AMPRNet supports the same transport and application protocols as the rest of the Internet, though there are regulatory restrictions on encryption and third-party traffic.

The AMPRNet is composed of a series of subnets throughout the world. Portions of the network have point-to-point radio links to adjacent nodes, while others are completely isolated.

Geographically dispersed radio subnets can be connected using an IP tunnel between sites with Internet connectivity. Many of these sites also have a tunnel to a central router, which routes between the 44 network and the rest of the Internet using static routing tables updated by volunteers.

As of October 2011 experimentation had moved beyond these centrally controlled static solutions, to dynamic configurations provided by Peer to Peer VPN systems such as n2n, and ZeroTier.

Address administration

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The allocation plan agreed in late-1986 reserved half of the address space (44.0/9 or ~8 million addresses) for use within United States territory and (44.128/9, the remaining ~8 million addresses) for the rest of the world.[10]

After the sale of 44.192.0.0/10 in 2019, the remaining Internet Protocol (IP) addresses are the 44.0.0.0/9 for USA subnets and 44.128.0.0/10 subnet for the rest of the world, available to any licensed amateur radio operator.[11] The IP address management and assigning of addresses is done by volunteer coordinators with the proviso "we do not provide the same level of response as a commercial organisation." These addresses can possibly be made routable over the Internet if fully coordinated with the volunteer administrators. Radio amateurs wanting to request IP addresses within the AMPRNet should visit the AMPRNet Portal.[12]

mirrorshades router

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San Diego Supercomputer Center, host of AMPRNet internet gateway, and CAIDA/UCSD network telescope

Since the 1990s most packets within the 44/8 range were arranged to transit via an IP tunnel using IP in IP encapsulation to/from a router hosted at the University of California, San Diego.[13] This forwarding router was originally named mirrorshades.ucsd.edu[13] and later gw.ampr.org[14] or "AmprGW".[11][14][15][16]

By 1996 higher-speed 56k modems briefly had greater throughput than was possible to forward via the "mirrorshades" central reflector router and back again.[17] Only IP addresses with an active Domain Name System (DNS) entry under ampr.org are passed by the packet filter for forwarding.[11][18]

By 19 August 1999 daily encapsulated IP in IP traffic was ~100 kilobits per second, peaking to 0.14 megabits per second.[19] During mid-2000, the majority of unique IP addresses seen on the University of California, San Diego connection from CERFnet began with the 44 prefix, except for 17% of IP addresses which did not.[20] In mid-2009 the mirrorshades server was upgraded and replaced after about ~1,100 days uptime.[21] A funding proposal in 2010 raised the possibility that "The legitimate traffic is also a potential research resource".[1]

UCSD Network Telescope

[edit]

Beginning in February 2001,[1][22][23][24] as part of backscatter research and the CAIDA/UCSD network telescope project, the whole of the 44/8 address block[25] was being advertised via the border gateway protocol (BGP) as a passive honeypot for Internet background noise and backscatter collection,[24][26] based in the Center for Applied Internet Data Analysis[note 1] at the San Diego Supercomputer Center.[29] On 15 July 2001 the network monitoring of 44.0.0.0/8 traffic recorded the spread of the Code Red II worm.[30] Prior to July 2001, the project had been logging unsolicited TCP SYN packets destined for IP addresses within 44.0.0.0/8; and after 19 July 2001 full incoming IP header logging took place.[31] The 44/8 IP address block was stated to have "high value to research".[32]

Capture data for August 2001, using data compression and retaining only IP headers was 0.5 gigabyte per hour.[33] In 2002 the block was 0.4% of all internet IPv4 address space.[34] By September 2003, traffic was 0.75 terabytes per month and costing $2,500 per month for bandwidth.[35] In October 2004 Limelight Networks began to sponsor the internet transit costs of the CAIDA network telescope.[35] In April 2009 the upstream rate limiting was removed, increasing the number of packets reaching the network telescope.[36] At the end of 2012, seaport.caida.org was the network telescope data capture server with thor.caida.org used for near real-time data access.[25][37][38] As of 2016, the 44/8 network was receiving backscatter from Denial-of-Service attacks (DoS) each measuring ~226 packets per second (mean peak average)[39] totalling 37 terabytes per month.[38]

Support was supplied by Cisco Systems under a University Research Board (URB) grant.[31][40] The project was funded by an Advanced Networking Infrastructure and Research (ANIR) award,[41] and Computer and Network Systems (CNS) award[42] from the National Science Foundation (NSF); the United States Department of Homeland Security (DHS);[41] and Network Modeling & Simulation (NMS) / Next Generation Internet Program (NGI) of the Defense Advanced Research Projects Agency (DARPA).[26][31]

  1. ^ Both "Cooperative Association for Internet Data Analysis" (CAIDA) and "Center for Applied Internet Data Analysis" (CAIDA) appear in academic texts.[27][28]
Feed
[edit]

In May 2017, the Center for Applied Internet Data Analysis provided a new server for the AMPRNet gateway, in a different building.[16] As of mid-2017 a passive monitoring configuration was in use, involving a network switch with port mirroring set to duplicate the incoming packets being seen by the AMPRNet gateway to the UCSD network telescope capture server.[24] The project funding proposal for "Sustainable Tools for Analysis and Research on Darknet Unsolicited Traffic" (STARDUST) specified a planned upgrading to 10 Gigabit Ethernet with a passive optical tap, in order to provide finer timestamping and avoid packet loss.[24]

By July 2018, the replacement 10 Gigabit Ethernet infrastructure, using an optical splitter and Endace capture card, was operational.[43]

Archives
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The archived intermittent captures for 2001‒2008 were 657 gigabytes.[44] The archived pcap captures from 2008‒2012 were 192 terabytes of data uncompressed.[45] In January 2012, five weeks of recent data were 5.5 terabytes uncompressed.[45] Beginning on 22 March 2012, the raw hourly compressed pcap traces from 2003‒2012 were transferred to the National Energy Research Scientific Computing Center (NERSC) for long-term storage and research data archiving.[36] This data migration of 104.66 tebibytes took one week at a sustained rate of 1.5 gigabits per second via the Energy Sciences Network (ESnet).[36]

For the 2012‒2017 period, 2.85 petabytes of data was collected (1.3 petabyte compressed).[25] As of 31 December 2017, the overall total collected by the UCSD Network Telescope stood at 3.25 petabytes (uncompressed), stored across 129,552 hourly files.[25]

Users of the collected data up to 2012 are requested to acknowledge that "Support for Backscatter Datasets and the UCSD Network Telescope is provided by Cisco Systems, Limelight Networks, the US Department of Homeland Security, the National Science Foundation, DARPA, Digital Envoy, and CAIDA Members."[46]

Block size

[edit]

The original Class A network allocation for amateur radio was made in the 1970s,[47] and recorded in September 1981,[7] which consisted of ~16 million IP addresses. As of 18 July 2019, the lower 75% of the 44/8 block (~12 million addresses) remained for amateur radio usage, with the upper 25% (44.192/10, ~4 million IP address) having been sold.[48][49]

Owing to IPv4 address exhaustion, by 2016 the 44/8 block was worth over $100 million.[8] The 44/8 routing prefix aggregation stopped being advertised on 4 June 2019.[50] John Curran, CEO of the American Registry for Internet Numbers registry stated that a request for the transfer of IP addresses had been received and reviewed in accordance with ARIN policy.[51]

On 18 July 2019, the designation recorded by Internet Assigned Numbers Authority was altered from "044/8 Amateur Radio Digital Communications"[52] to "044/8 Administered by ARIN".[53] On 18 July 2019, there was a sale of 44.192.0.0/10 address space to Amazon Technologies Inc, which was the highest bidder,[49] for use by Amazon Web Services.[54] AMPRNet subsequently consisted of 44.0/9, and 44.128/10,[55] with no plans to sell any more address space.[56]

The aspiration expressed by those involved in the sale was that money be held by a non-profit 501(c)(3) organization for the advancement of amateur radio.[57] The sale raised over $50 million.[56] Prior to sale, addresses in the 44.192/10 block had been allocated to amateur radio areas for the outer space-amateur radio satellite service,[58][59][60] to roaming,[60] Oceania,[58][59][60] Antarctica,[58][59][60] the Arctic,[58][59][60] Italy for Centro Italiano Sperimentazione ed Attività Radiantistiche (CisarNet)[61][62] Germany for Stuttgart/Tübingen,[63] Eppstein,[63] plus the Germany/pan-European Highspeed Amateur-radio Multimedia NETwork [de] (HAMNET).[62][64][65]

Responses

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Paul Vixie stated after the sale of IP address space that "ampr.org can make better use of money than IP space in fulfilling its nonprofit mission, at this stage of the game."[66]

Doug Barton, a former manager of Internet Assigned Numbers Authority, said the "reaction that we're seeing now is 100% predictable ... that doesn't change anything about my opinion that the sale itself was totally reasonable, done by reasonable people, and in keeping with the concept of being good stewards of the space.[67]

Governance

[edit]

Initial committee

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An Amateur Radio Digital Communications committee was formed to offer advice on digital standards to the American Radio Relay League (ARRL) board of directors, following a meeting in 1981. The original working name was the "ARRL Ad Hoc Committee on Digital Communication", abbreviated to "digital committee".[68] During the mid-1980s, the committee had been meeting twice per year: during the middle of the year, and again at the annual Computer Networking conference.[69]

In September 1987, the committee recommended the list of frequencies that would be used in North America for packet radio and digital communications.[70] In January 1988, the committee held a meeting to standardise AX.25 version 3.[71] In March 1988, the "Packet Radio Frequency Recommendations" were published by the committee.[72]

During early 1993 the committee and ARRL board of directors were working on guidelines for semi-automatic digital stations, with the proposals passed to the Federal Communications Commission.[73]

Non-profit transition

[edit]
Amateur Radio Digital Communications, Inc.
Year US$, assets at end of year
2012[a]
456($-842 equity)
2013[b]
830($-1,584 equity)
2014[c]
6,399($3,700 equity)
2015[d]
6,567($3,558 equity)
2016[e][f]
6,717($3,708 equity)
2017[f]
2,621($1,731 equity)
2018[g]
13,829($-7,855 equity)
2019[h]
109,130,548
2020[i]
127,858,353
2021[j]
135,676,708
2022[k]
107,895,897
2023[l]
117,236,719

On 6 October 2011 a Californian non-profit company was founded with the name of "Amateur Radio Digital Communications", and recorded by the State of California on 11 October 2011 with an address of "5663 Balboa Avenue, Suite 432, San Diego, California[74]—a UPS store address. On 22 June 2012,[75] 29 September 2015,[76] and 18 September 2017,[77] filings were made listing the company officers as:

Brian Kantor
President[75]: 5  or Chief Executive Officer[76][77]
Erin Kenneally
Secretary[75]: 5 [76][77]
Kimberly Claffy
Treasurer[75]: 5  or Chief Financial Officer[76][77]

In 2011, the American Registry for Internet Numbers approved a request to change the registration of the whole 44/8 network block from an individual contact, to the "Amateur Radio Digital Communications" non-profit company.[78]

Activities were to "conserve scarce AMPRNet Internet protocol resources, and to educate networks users on how to efficiently utilize these resources as a service to the entire Internet community" initiated "in the second half of 2012 by the President via communications with American Registry for Internet Numbers (ARIN)".[75]: 3  Plans included "the issuance of grants and other financial support to educational institutions, foundations and other organizations. [...] expected to commence in 2013 via a joint effort of the three founding Directors [...]".[75]: 3 

During December 2017 Kantor announced his retirement from University of California San Diego.[14][79] Re-stated (changed) articles of incorporation for the "Amateur Radio Digital Communications" non-profit were signed on 13 December 2017,[80] and filed on 17 December 2017.[80] In May 2019, Kantor signed an agreement extending UCSD/CAIDA's use of Amprnet addresses for data collection until 31 July 2023.[81]

Brian Kantor died in November 2019. In February/March 2020, the Center for Networked Systems (CNS) of the University of California, San Diego (UCSD) received $225,000, given by ARDC to allow financial endowment of a student scholarship in the name of Alan Turing and honouring Brian Kantor.[82]

Distributions

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Radome on Green Building at MIT saved by ARDC support in 2021

In May 2021, ARDC provided a one-off grant of $1.6 million to the Massachusetts Institute of Technology amateur radio club (W1MX) to save and rebuild the radome on top of the MIT Green Building (building 54).[83]

In November 2021, ARDC awarded a five-year grant, for a total of $1.3 million, to support US-based activities around Amateur Radio on the International Space Station (ARISS-USA).[84]

Digital Library of Amateur Radio and Communications
[edit]

In January 2022, the Internet Archive received a grant of $0.9 million for assembling a Digital Library of Amateur Radio and Communications (DLARC).[85] Internet Archive began the project in earnest in September 2022, and began seeking contributions of material in October. [86] By November, 2022 the library had grown to 25,000 items. [87] In January 2023 the library held over 51,000 items including more than 3,300 books and magazines available via controlled digital lending.[88]

Other ARDC grants
[edit]

An updated list of ARDC grants is maintained on their website at [1]. Information on applying for a grant is at [2].

See also

[edit]

References

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Further reading

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

AMPRNet

View on Grokipedia
from Grokipedia
AMPRNet, short for Amateur Packet Radio Network and also known as 44Net, is a block of IPv4 addresses (44.0.0.0/9 and 44.128.0.0/10) allocated exclusively to licensed operators for experimenting with digital communications and IP networking over radio frequencies. Originating in the mid-1980s with the pioneering use of TCP/IP protocols over , AMPRNet has evolved to support connections via radio links, IP tunneling across the public , and occasionally BGP peering, enabling a global mesh of amateur-operated nodes for research and education in radio-based data transmission. Managed by the nonprofit Amateur Radio Digital Communications (ARDC), the network emphasizes non-commercial, secure experimentation to advance technologies, including services like DNS resolution under the ampr.org domain and real-time node mapping for tracking activity. Its defining characteristic lies in bridging traditional radio with protocols, contributing to early developments in networking while adhering to regulations that prioritize technical self-training and innovation over routine communication.

History

Origins in the 1980s

In 1981, amateur radio operator Hank Magnuski (KA6M) secured the IPv4 address block 44.0.0.0/8 from the Internet Assigned Numbers Authority (IANA), allocating over 16.7 million addresses exclusively for licensed amateur radio operators worldwide to support digital communications experiments. This initiative arose from the growing interest in packet radio within the amateur community during the late 1970s and early 1980s, where operators sought to extend packet-switching techniques—initially developed for wired networks like ARPANET—to radio frequencies for resilient, infrastructure-independent data transmission. Magnuski's request emphasized the use of TCP/IP protocols over amateur packet networks, enabling hams to conduct research in areas such as network reliability and long-distance digital messaging without reliance on commercial telephony or leased lines. A volunteer group soon formed to administer the address space informally, laying the groundwork for AMPRNet as a self-governed network distinct from the public Internet. Early operations integrated IP routing with AX.25 protocols on VHF and UHF amateur bands, using digipeaters and gateways to propagate packets between stations, often achieving connections spanning hundreds of kilometers via multi-hop relays. By the mid-1980s, these efforts had established initial nodes for experimentation, focusing on applications like bulletin boards, file transfers, and nascent email systems tailored to radio's variable propagation conditions, thereby fostering a parallel IP ecosystem for scientific and technical pursuits within amateur radio constraints.

Expansion and Milestones in the 1990s and 2000s

In the early 1990s, AMPRNet expanded through the deployment of IP-in-IP encapsulation protocols, allowing amateur radio packet networks to tunnel traffic over commercial internet backbones for inter-regional connectivity. A key was the establishment of a central router at the (UCSD), which began handling transit for the 44/8 address block around 1990, aggregating routes from dispersed gateways and improving global reachability for amateur operators. This infrastructure shift enabled more efficient packet forwarding beyond local VHF/UHF radio links, supporting TCP/IP experimentation across continents despite regulatory constraints on direct radio-to-internet bridging. Peak network activity occurred between 1985 and 1995, driven by growing adoption of affordable terminal node controllers (TNCs) and NOS software stacks like KA9Q, which facilitated hundreds of gateways worldwide. By mid-decade, coordinators managed subnetwork allocations, with documented lists emerging by September 1994 to handle increasing demand for 44.x.x.x addresses among U.S. and international hams. Higher-speed modems, such as 56 kbps units tested in , briefly enhanced throughput on HF links, though bandwidth limitations and channel contention persisted as growth challenges. Into the 2000s, AMPRNet's expansion slowed as widespread home reduced reliance on radio-based networking, shifting focus from rapid node proliferation to sustained maintenance. Volunteer coordinators, operating under evolving administrative bodies, allocated subnetworks and peered with providers, though utilization remained sparse with only about 40,000 addresses actively assigned from the 16.7 million available by the early . Ownership of the 44/8 block transitioned in the late 1990s through early from early stewards like Hank Magnuski (KA6M) to precursors of the Amateur Radio Digital Communications (ARDC), formalizing non-profit oversight amid rising IPv4 scarcity pressures post-1996 Telecommunications Act. These efforts preserved the network for niche applications, including scientific monitoring like worm propagation studies via UCSD's integration.

Developments in the 2010s and 2020s

In 2011, Amateur Radio Digital Communications (ARDC) was established as a non-profit foundation to oversee the management and preservation of the AMPRNet address space for experimentation. This transition aimed to ensure long-term sustainability amid evolving protocols and declining traditional usage, with ARDC focusing on non-commercial allocation to licensed operators. A significant milestone occurred in July 2019 when ARDC sold the 44.192.0.0/10 block—comprising approximately 4 million IPv4 addresses—to Amazon Technologies Inc. for use in , reducing the active AMPRNet space to 44.0.0.0/9 and 44.128.0.0/10. The transaction, with proceeds of $108 million announced in October 2020, provided funding for ARDC's endowment to support digital initiatives while retaining the core space for experimental purposes. Throughout the 2020s, ARDC enhanced accessibility via tools like the startampr software, with released in late 2024 incorporating a fix to prevent unencapsulated traffic leakage from tunnels to the public . A 2023 survey by ARDC assessed user needs and , informing ongoing improvements in address allocation and . In October 2025, an IETF draft proposed reserving the block 44::/16 exclusively for 44Net, extending AMPRNet's experimental framework into dual-stack operations. These efforts have sustained the network's role in amateur digital communications, increasingly leveraging tunnels over the alongside legacy radio links.

Technical Protocol

Core Design and Packet Radio Integration

AMPRNet employs a TCP/IP-based architecture tailored for amateur radio, leveraging the IANA-reserved 44.0.0.0/8 IPv4 address space (commonly termed 44Net) to enable licensed operators to experiment with digital networking protocols. The network forms a decentralized mesh of interconnected nodes, including routers and gateways, that support full IP protocol suite functionality such as Telnet, FTP, and ping, routed via modified protocols like RIP44 (a UDP-based variant of RIP on port 520) and BGP for dynamic path selection. This structure avoids a centralized star topology, instead relying on peer-to-peer IPIP tunnels to encapsulate 44Net traffic within standard IPv4 packets for transit over the public internet, with gateways filtering and forwarding to prevent direct amateur-to-commercial interconnects in compliance with FCC regulations. Packet radio integration anchors AMPRNet's wireless segments to the protocol, a 1984-standardized derived from X.25 and optimized for amateur RF channels, which encapsulates IP datagrams into variable-length frames for transmission. These frames carry TCP/IP payloads over VHF/UHF bands at speeds constrained by spectrum allocations—typically 1200 for narrowband FM, extensible to 9600 or higher on microwave allocations using high-speed multimedia (HSMM) modes like 802.11 derivatives. Terminal Node Controllers (TNCs) or software-defined equivalents, such as Direwolf, handle modulation/demodulation and digipeating, interfacing with hosts via the protocol to present ports as raw serial devices for direct IP stack attachment, bypassing traditional TNC firmware limitations. Pioneering software like Phil Karn's NOS (developed in 1985 for and later ported) integrated link-layer services with TCP/IP, providing connection-oriented reliability, fragmentation, and routing over error-prone radio paths through (ARQ) mechanisms inherent to . Modern Linux kernels extend this with native drivers, enabling tools like kissattach to bind TNC interfaces as network devices (e.g., ax0) for seamless IP forwarding, while IPIP tunnels at edge gateways merge radio-local subnets into the broader AMPRNet fabric without exposing amateur traffic to unrestricted . This layered approach— for local RF hops, IP for end-to-end routing—facilitates resilient, low-bandwidth digital services like relays and remote , though propagation delays and interference necessitate robust error handling beyond standard TCP assumptions.

Address Administration and Infrastructure

The 44.0.0.0/9 and 44.128.0.0/10 IPv4 address blocks are designated for AMPRNet, originally allocated as 44.0.0.0/8 in 1981 by for digital communications experimentation. Address administration is handled by Amateur Radio Digital Communications (ARDC), a non-profit entity, through an automated portal at portal.ampr.org. Only licensed operators may request allocations, which must support non-commercial uses advancing networking, such as integration or research. Allocation begins with users creating a secure account using their callsign, password, , and location details, followed by selecting available address blocks via a geographic on the portal. Requests for small (e.g., /28 providing 14 usable addresses or /29 with 6) are typically automated, while larger blocks require review and approval by volunteer coordinators to ensure compliance with usage policies. Approved allocations include registration under ampr.org, managed by regional coordinators listed on the portal. The 44.128.0.0/16 is reserved specifically for testing purposes. AMPRNet infrastructure forms a distributed mesh topology, interconnecting nodes via amateur radio packet links (e.g., over VHF/UHF) and Internet-based encapsulation methods like IP-in-IP tunneling or VPNs. Traffic between the public and AMPRNet passes through the AmprGW gateway hosted at the , which filters packets, enforces access controls, and facilitates forwarding while supporting protocol interoperation among tunnels, VPNs, and BGP sessions. Routing relies primarily on the RIP44 protocol via software like ampr-ripd for dynamic advertisement within the network, with BGP peering permitted only after ARDC authorization for public announcements, often requiring ISP coordination. Gateways at user sites encapsulate AMPRNet packets for transit over commercial Internet links, ensuring separation from public IPv4 space while enabling global reach among thousands of nodes.

Network Monitoring and Research Tools

Operators of AMPRNet gateways and nodes employ standard diagnostic utilities, including ping for reachability testing and for path analysis, to monitor connectivity and troubleshoot issues within the 44.0.0.0/8 . These tools function over both radio links and IP-in-IP tunnels that interconnect the network. A specialized diagnostic server hosted at kb3vwg-010.ampr.org offers enhanced services such as source IP verification, speed tests, ping, and , restricted to queries originating from valid AMPRNet addresses to prevent external probing. Routing propagation and network state monitoring depend on RIP44, a customized implementation of version 2 tailored for AMPRNet's encapsulation requirements and constraints. Gateways exchange RIP44 updates to maintain tables, enabling operators to detect topology changes, such as node outages or link failures, through log analysis of routing advertisements. Software like startampr, distributed for Linux-based gateways, includes scripts that facilitate route saving and initialization, aiding in post-failure diagnostics. For research purposes, AMPRNet supports experimentation with protocols, including encapsulation and wireless mesh , using tools like for packet capture and analysis on gateway interfaces to study propagation delays and error rates over RF paths. Visualization aids such as Ampr-map provide graphical overviews of active nodes and tunnels, derived from aggregated data, assisting researchers in mapping network extent and identifying underutilized segments. These capabilities align with AMPRNet's foundational role in advancing digital communications since its inception in 1985.

Governance and Management

Initial Committee and Early Administration

The 44.0.0.0/8 IPv4 address block, designated for amateur radio digital networking and later known as AMPRNet or Network 44, was allocated in 1981 to Hank Magnuski, KA6M, by Jon Postel, the Internet Assigned Numbers Authority's early overseer of address distributions. This assignment provided approximately 16.8 million addresses, initially intended for experimental packet-switched communications among licensed amateur radio operators. Magnuski, a key early proponent, coordinated the nascent infrastructure, including gateways connecting radio links to the broader ARPANET-derived Internet. In the mid-1980s, AMPRNet's operational foundation was established by co-founders Phil Karn, KA9Q, and Brian Kantor, WB6CYT, who implemented TCP/IP protocols over amateur packet radio using software like KA9Q NOS. Karn developed core NOS software enabling reliable end-to-end networking, while Kantor, based at the , managed central backbone routers and Internet gateways, handling routing tables and connectivity to commercial networks. Early administration remained informal, with the founders directly overseeing node registrations, subnet delegations to regional coordinators, and maintenance of radio encapsulations for IP traffic, without a formalized governing body. Address space distribution began under Magnuski's custodianship and transitioned to Karn and Kantor, who allocated subnets ad hoc to active nodes based on operational needs, such as geographic coverage via VHF/UHF repeaters and HF links. This decentralized approach relied on voluntary participation from operators, with no central registry until later developments; disputes over allocations were resolved through direct communication among administrators. By the late , the network supported hundreds of nodes, but administrative burdens grew with expansion, prompting discussions on standards via groups like the Tucson Amateur Packet Radio (TAPR).

Transition to Non-Profit Entity

Prior to 2011, AMPRNet's governance relied on informal arrangements among volunteer operators and technical committees, with administration handled through coordination and individual contacts registered with registries like ARIN. This structure, while functional for experimental networking, lacked formal organizational stability and long-term stewardship mechanisms for the 44.0.0.0/8 block. In October 2011, Amateur Radio Digital Communications (ARDC) was established as a California-based 501(c)(3) nonprofit public benefit corporation to formalize and oversee AMPRNet operations. Founded by key figures including Brian Kantor (WB6CYT), a pioneer in AMPRNet's early development, ARDC assumed responsibility for managing the network's IPv4 address space, ensuring its exclusive use for amateur radio experimentation and digital communications. This transition coincided with ARIN's approval to re-register the entire 44/8 block under ARDC's organizational contact, shifting from individual stewardship to institutional control. The move to nonprofit status aimed to secure AMPRNet's future by providing a dedicated entity for policy enforcement, subnet allocation to licensed operators, and compliance with amateur radio regulations prohibiting commercial use. ARDC's charter emphasized non-profit applications, such as supporting research in protocols and maintaining infrastructure for global connectivity, while prohibiting resale or profit-driven exploitation of allocated addresses. By centralizing authority, ARDC addressed prior vulnerabilities in informal governance, enabling sustained technical evolution and resource allocation without reliance on transient volunteer efforts.

Address Space Allocation and Sales

The 44.0.0.0/8 IPv4 address block, comprising approximately 16.7 million addresses, was originally allocated to Hank Magnuski (KA6M) in by the Network Information Center for use in networking experiments. This delegation supported the development of AMPRNet as a dedicated network for digital communications, distinct from the public . Management of the block transitioned to Amateur Radio Digital Communications (ARDC), a non-profit entity established in 2011, which assumed responsibility for administration and conservation. In 2019, ARDC sold the 44.192.0.0/10 subnet—containing about 4 million addresses—to , reducing the retained AMPRNet space to roughly 12 million addresses across 44.0.0.0/9 and portions of other sub-blocks. The transaction yielded $108 million, with proceeds directed toward ARDC's grants program to fund digital innovation, though it drew criticism from some operators for lacking community consultation prior to execution. This sale reflected the underutilization of the full /8 block in amateur applications amid IPv4 scarcity in commercial markets, prioritizing financial sustainability over hoarding unused space. Allocations of remaining AMPRNet addresses to individual licensed operators occur at no cost through ARDC's online portal at portal.ampr.org, requiring applicants to hold a valid amateur license and intend use for radio-linked digital networking experiments compliant with ARDC's . Requests specify a size (e.g., /32 for single hosts or /29 for small networks, with /24 minimum for BGP ), regional partition alignment, and connection method such as IPIP tunneling, direct BGP via an ISP, or pure radio links. Approvals are reviewed by administrators to ensure alignment with purposes, excluding commercial or non-radio uses, and granted allocations must be registered for within the AMPRNet . This process enforces scarcity and relevance, preventing abuse while enabling global experimentation.

Applications and Impact

Primary Uses in Amateur Radio

AMPRNet enables operators to conduct experiments in digital networking using protocols transmitted over radio frequencies, leveraging the allocated IPv4 block 44.0.0.0/8 for exclusive ham use. This facilitates the development and testing of systems, where IP packets are encapsulated in frames for modulation onto VHF/UHF bands at data rates of 1200–9600 baud or HF at 300 baud. Such setups allow for direct TCP/IP connectivity over RF links, supporting full protocol stacks including routing via tools like RIP44 for dynamic address propagation. Primary applications encompass messaging and data services tailored to amateur radio constraints, including for radio transmission, APRS for real-time position tracking and telemetry, and legacy bulletin board systems (BBS) for asynchronous information sharing among operators. More advanced uses extend to multimedia, such as digital voice via or VoIP, video conferencing, Web-SDR for remote access, and digital amateur television (D-ATV), all routed through AMPRNet infrastructure. The network also underpins emergency and resilient communications, acting as a fallback when commercial fails by providing IP-based services like and remote station control over radio paths or IPIP tunnels. Operators utilize AMPRNet gateways—often software like KA9Q NOS—to bridge radio segments with tunnels, enabling global reach while adhering to regulations that prohibit direct peering. This experimentation advances computer services for the community, such as networked diagnostics and telemetry for balloon launches or rover stations, fostering innovation in radio digital modes.

Key Achievements and Contributions

AMPRNet pioneered the integration of TCP/IP protocols with amateur packet radio, enabling wide-area digital networking over radio frequencies as early as the early 1980s. This allowed amateur radio operators to experiment with internet-style communications in environments prone to signal loss and interference, leading to discoveries in TCP/IP enhancements for reliable data transmission over congested and unreliable links. Such innovations, first identified through AMPRNet operations, informed broader networking practices by demonstrating adaptations for non-wired media. The network's dedicated Class A address block, originally 44.0.0.0/8 allocated in September 1981, provided approximately 16 million IP addresses exclusively for amateur experimentation, fostering research into protocol efficiency and radio-based internetworking without commercial interference. Over four decades, AMPRNet has supported educational efforts in networking for thousands of operators, advancing the technical capabilities of amateur radio digital modes. A major financial contribution arose from the strategic sale of unused portions of the address space; in 2020, 4 million consecutive AMPRNet addresses were sold to Amazon Web Services for $108 million, with proceeds managed by Amateur Radio Digital Communications (ARDC) to fund grants, scholarships, and infrastructure for digital communications projects. These funds have supported emergency communications enhancements, including equipment for resilient messaging systems during outages, thereby amplifying amateur radio's role in public service and disaster response.

Criticisms and Operational Challenges

AMPRNet's reliance on amateur radio frequencies imposes inherent bandwidth constraints, with typical data rates limited to 1,200–9,600 bit/s on VHF and UHF links, and as low as 300 bit/s on HF due to spectrum limitations and modulation inefficiencies. These speeds hinder high-throughput applications, exacerbating latency in and making real-time services impractical compared to wired IP networks. Propagation challenges in radio environments, including signal and interference, further degrade reliability, requiring robust error correction that consumes additional overhead. Security vulnerabilities represent a persistent operational challenge, as the network's —often using unencrypted protocols over radio—exposes nodes to interception and exploitation, with documented cases of botnets propagating via legacy Systems (BBS) in segments. operators, while technically proficient in radio, frequently neglect modern cybersecurity practices, such as firewalling or intrusion detection, leading to risks like address spoofing and denial-of-service attacks that necessitate ISP ingress filtering and centralized tunneling via gateways like UCSD's low-bandwidth router. Regulatory prohibitions on obscured communications in amateur bands complicate adoption of , conflicting with security-by-default designs in contemporary IP applications and limiting with secure services. Governance has faced criticism over address space management, particularly the Amateur Radio Digital Communications (ARDC) entity's sale of underutilized portions of the 44.0.0.0/8 block, which generated over $108 million by October 2020 but sparked debate about , as the allocation was originally designated for self-administered amateur use by global radio operators. Opponents argued the sales deviated from the community's experimental ethos, potentially prioritizing revenue over preservation, though ARDC directed proceeds toward grants for digital amateur projects. Inadequate documentation and verification processes have also impeded participation, with the AMPRNet plagued by outdated guides, spelling errors, and incomplete setup instructions, contributing to low adoption and consolidation pressures on legacy operators. Recent mandates for user verification aim to enhance trust but introduce access barriers for newcomers.

Future Directions

IPv6 Adoption and Technical Evolution

AMPRNet has historically operated using the IPv4 address block 44.0.0.0/8, with traffic encapsulated in tunnels over the public to connect nodes. This architecture, established in the , relies on IPv4 endpoints for tunnel ingress and egress, limiting native integration without structural changes. As of December 2024, no comprehensive conversion of AMPRNet to has occurred, with community consensus indicating that a direct migration is improbable; instead, parallel IPv6-based networks for experimentation are anticipated to emerge. IPv4 address scarcity has accelerated discussions on evolution, particularly after sales of portions of the 44/8 block—such as 44.192.0.0/10 withdrawn from amateur use in 2019—which generated funds for the Amateur Radio Digital Communications (ARDC) but underscored the need for IPv6 alternatives. ARDC, which administers the remaining space, has emphasized as the long-term direction for digital communications, citing widespread global and the exhaustion of IPv4 resources. A 2023 ARDC survey of 44Net users revealed IPv6 interest primarily as an experimental or future capability, with limited current implementation beyond isolated tests using non-AMPR prefixes like 2607:f3f0::/32 for local amateur setups. In October 2025, an IETF individual submission (draft-ursini-44net-ipv6-allocation-00) proposed allocating an prefix as a counterpart to 44Net, arguing for its necessity due to the network's unique technical demands—such as low-bandwidth, high-latency wireless links—and social role in non-commercial experimentation. The draft highlights that while general adoption exceeds 40% globally as of early 2025, amateur radio networks lag due to entrenched IPv4 tunneling, but a dedicated allocation could enable seamless evolution without disrupting legacy operations. Technical advancements under consideration include stateless address autoconfiguration (SLAAC) for node addressing and hybrid tunnel protocols to bridge IPv4 remnants, though full rollout depends on IETF endorsement and community infrastructure upgrades. These efforts reflect a pragmatic shift toward 's abundant addressing to sustain AMPRNet's experimental ethos amid commercial IPv4 pressures.

Ongoing Projects and Community Initiatives

The AMPRNet community maintains active engagement through the 44Net mailing list, hosted on ARDC's Groups.io platform, where licensed amateur radio operators discuss network operations, troubleshooting, and enhancements. As of October 2025, the list has over 548 members and sees monthly volumes exceeding 100 messages, covering topics such as IPIP tunnel configurations, routing issues, and infrastructure upgrades. This volunteer-driven forum facilitates real-time collaboration among gateway operators worldwide, with recent threads addressing policy-based routing and integration with modern Linux distributions. A key ongoing project is the development and maintenance of startampr, a suite of Bourne Again Shell scripts designed to automate the setup of AMPRNet gateways on or Ubuntu-based systems. Initiated by KB3VWG and contributors from the 44Net community, the tool configures IPENCAP tunnels, enables AMPR RIP44 routing, and handles boot-time initialization for experimentation. Documentation was last updated on December 12, 2024, reflecting iterative improvements to support static IPv4 addressing without NAT. Software tooling efforts include the ampr-ripd daemon, a routing protocol implementation for AMPRNet that propagates updates via RIP44. This package was integrated into the 24.10 release, enabling easier deployment on embedded devices for gateway operations. Community contributions, such as those documented by operator K2IE, emphasize compatibility with to isolate AMPR traffic. ARDC supports broader initiatives through its grants program, funding experiments in digital communications that align with AMPRNet's experimental ethos, including tools for and IP-over-radio links. While specific AMPRNet grants are not itemized publicly, the organization's management of the 44Net address portal encourages self-registration and subdomain allocation for new nodes, fostering grassroots expansion.

References

  1. https://wiki.ampr.org/wiki/Home
  2. https://www.ardc.net/44net/
  3. https://wiki.ampr.org/wiki/FAQ
  4. https://www.ardc.net/about/faq/
  5. https://www.qsl.net/yb0emj/amprnet.html
  6. https://www.caida.org/funding/cici-canis/cici-canis_proposal/
  7. https://www.qsl.net/kb9mwr/wapr/tcpip/amprnet.html
  8. http://www.jdunman.com/ww/AmateurRadio/Networking/amprnet.htm
  9. https://kz2x.radio/posts/amprnet/
  10. https://news.ycombinator.com/item?id=20475855
  11. https://www.ardc.net/wp-content/uploads/2024-brochure-44net-20240408-v2-smallest-file-size.pdf
  12. https://toonk.io/aws-and-their-billions-in-ipv4-addresses/index.html
  13. https://nediv.arrl.org/2020/10/12/sale-of-amateur-radio-amprnet-tcp-ip-addresses-raised-108-million/
  14. https://wiki.ampr.org/wiki/Startampr
  15. https://www.ardc.net/wp-content/uploads/ARDC-44net-Survey-Assessment-Results-sm.pdf
  16. https://www.ietf.org/archive/id/draft-ursini-44net-ipv6-allocation-00.html
  17. https://themodernham.com/modern-introduction-to-packet-radio-ax25-aprs-and-tcp-ip/
  18. https://ardc.groups.io/g/44net
  19. https://www.ardc.net/44net/joining/
  20. https://wiki.ampr.org/wiki/Services
  21. https://wiki.ampr.org/wiki/K2IE
  22. https://www.ardc.net/about/
  23. https://files.tapr.org/meetings/DCC_2016/DCC2016-IPV6.pdf
  24. https://www.arrl.org/news/amprnet-cofounder-brian-kantor-wb6cyt-sk
  25. https://files.tapr.org/psr/psr143.pdf
  26. https://wiki.ampr.ari.it/images/1985_Kantor.pdf
  27. https://www.k0nr.com/wordpress/2021/10/whats-this-ardc-grant-thing/
  28. https://www.ardc.net/about/who-we-are
  29. https://www.amateurradio.com/tag/ardc/
  30. https://www.ardc.net/about/legal/terms-of-service/
  31. https://www.kb6nu.com/sale-of-amateur-radio-amprnet-tcp-ip-addresses-raised-108-million/
  32. https://www.ardc.net/44net/portal/
  33. https://www.arrl.org/news/millions-of-amprnet-internet-addresses-sold-to-fund-grants-and-scholarships
  34. https://www.arrl.org/news/ardc-grant-provides-areslax-with-sophisticated-noise-location-capabilities
  35. https://themodernham.com/bbs-botnet-the-packet-radio-cybersecurity-crisis-in-ham-radio/
  36. https://news.ycombinator.com/item?id=24753654
  37. https://ewpratten.com/blog/amprnet-bgp
  38. https://wiki.ampr.org/wiki/Verification
  39. https://wiki.ampr.org/wiki/Ipv6
  40. https://www.reddit.com/r/amateurradio/comments/cf2cbo/see_ya_448/
  41. https://ardc.groups.io/g/44net/topics
  42. https://www.k2ie.net/blog/tag/ampr-ripd/
  43. https://portal.ampr.org/
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