Yes. See the man pages for
slattach, sliplogin,
pppd and
ppp.
pppd and ppp provide support for both incoming and outgoing
connections. Sliplogin deals exclusively with incoming connections and
slattach deals exclusively with outgoing connections.
These programs are described in the following sections of the handbook:
If you only have access to the Internet through a "shell account", you may want to have a look at the slirp package. It can provide you with (limited) access to services such as ftp and http direct from your local machine.