This article is from the Mac communications FAQ, by Bruce L Grubb BruceG6069@aol.com with numerous contributions by others.
Regardless of whether you using Classic or Open Transport networking
(see [4.2]) there are some common hardware and software requirements:
a program that implementes the Defense Advanced Research Projects
Agency (DARPA) TCP/IP Protocols (see [4.1])
a direct connection to an Ethernet or TokenRing network, PPP
dialup connection, or a connection to a LocalTalk network with
a DDP-IP router such as a Shiva FastPath, Cayman Gatorbox,
Webster Multigate, or Compatible EtherRoute TCP.
Both Classic Networking and Open Transport use a TCP/IP Control Panel
plus a PPP extension. MacTCP 2.0.6 (Classic Networking) requires a
Macintosh Plus or later CPU and System 6.0 or better and became part
of the OS with System 7.5. TCP/IP (Open Transport) became part of the
MacOS with 7.5.3 and needs OT/PPP 1.0 or better.
Both programs provided a standard interface to TCP/IP network
hardware, and makes it possible for more than one TCP/IP based
application to run on a Macintosh at any one time. For example,
you can simultaneously use a Telnet program, an FTP program, and
share a filesystem via NFS when you use MacTCP or OT to provide the
interface to your TCP/IP network.
For more detailed information regarding connecting a Macintosh
to a TCP/IP network using MacTCP consult Eric Behr's report on MacTCP
<http://www.math.niu.edu/~behr/docs/mactcp.html>. This report also
provides a lot of useful information for first-time Macintosh
For those interesting in using Open Transport please consult Mark
Sproul's <http://msproul.rutgers.edu/macintosh/OpenTpt.html> and
Apple's <http://www.apple.com/macos/opentransport/> Open Transport