The Point-to-Point Protocol (PPP) provides a standard way to establish
a network connection over a serial link.

This package includes the PPP daemon (pppd), which negotiates with
the peer to establish the link and sets up the ppp network interface.
Pppd includes support for authentication, so you can control which other
systems may make a PPP connection and what IP addresses they may use. It
also has multilink support.

It also includes chat, for defining a automated conversational exchange
with a modem for establising a connection between the ppd and the
remote's pppd.

And pppstats reports the PPP-related statistics at regular intervals for
the specified PPP interface, such as properties and volume of packets
received and transmitted.

Paul Mackerras is the original author of a lot of this pppd code.