Amateur Radio Digital Communications, Inc.

Lore & Background

The use of Internet protocols TCP/IP on amateur 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 for amateur radio users worldwide, prior to Internet flag day (1 January 1983) when the ARPANET Network Control Protocol was replaced by TCP. The initial name used by Jon Postel in RFC 790 was the 'Amateur Radio Experiment Net'. Originally the amateur link layer protocol AX.25 carried several competing higher level protocols, with TCP/IP a minority due to complexity and high protocol overhead. 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 a few years the public Internet made these solutions obsolete.

Reader's Guide

The AMPRNet is connected by wireless links and Internet tunnels. Due to bandwidth limitations, 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 equipment on 2.4 GHz and 5 GHz is now used on nearby amateur frequencies to provide 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 network is composed of subnets worldwide, with point-to-point radio links and isolated portions. Geographically dispersed subnets can be connected using IP tunnels. As of October 2011, experimentation moved to dynamic configurations provided by peer-to-peer VPN systems such as n2n and ZeroTier. The allocation plan agreed in late-1986 reserved half the address space (44.0/9) for the United States and the other half (44.128/9) for the rest of the world. After the 2019 sale of 44.192.0.0/10, remaining addresses are available to any licensed amateur radio operator, managed by volunteer coordinators.

Did You Know?

• The 44/8 network was used as a network telescope beginning in 2001, recording the spread of the Code Red II worm in July 2001.
• As of December 2009, approximately 1% of inbound traffic to the 44/8 network was legitimate amateur radio traffic.
• By 2016, the European-based HAMNET offered a multi-megabit IP network with 4,000 nodes covering central Europe.
• The mirrorshades router at UCSD has forwarded most 44/8 packets via IP-in-IP encapsulation since the 1990s.