Amateur radio already used TCP/IP on packet radio network, long before the appearance of the public Internet. The class A 44 netblock of 16.7 Million IP addresses was set aside for amateur radio users worldwide it was secured in the 1970s by Hank Magnuski, when the internet was in its infancy.
The AMPRNet is connected by links over amateur packet radio. Due to the bandwidth limitations of the radio spectrum, links are usually restricted to a maximum of 9600 baud and are commonly 1200 baud and on occasion as low as 300 baud. The AMPRNet fully supports TCP/IP allowing for support of FTP, , Ping, Finger and . Recently the AMPRNet has gained radio link speeds upwards of 108 Mbit/s using HSMM.
Currently the AMPRNet is composed of a series of subnets throughout the world. Many subnets are also connected via tunnels over the Internet. Portions of the network have radio links to adjacent nodes, while others are completely isolated.
Geographically dispersed radio subnets are meshed together using an IP tunnel at sites with Internet connectivity. In general, these sites also have a tunnel to a central site at UCSD through the host mirrorshades.ucsd.edu which offers a route between the 44/8 network and the rest of the Internet. In countries where permitted by the relevant regulatory authority, amateur radio operators are able to access resources on the Internet.