You have two major options.
cslip and ppp.

ppp is probably your best bet with NetBSD but some people have said
that cslip is faster, I do not know.
Read the man pages for pppd and sliplogin.
Files to look at are /etc/ppp/*
/etc/phones
/usr/sbin/pppd
/etc/sliphome
/etc/ppp/ip-up
/etc/ppp/ip-down

cslip is a program you'd have to get and compile.

Hope that helps.

-ASC

On Wed, 20 Mar 1996 21:42:34 +1000 (EST) 
 Salvatore Salamone <saausa@wurley.apana.org.au> wrote:

 > 
 > 
 > I have installed the NetBSD & everything seems ok, now I just want to=20
 > connect by modem to another unix, this unix (server u may call it) has a=20
 > internet connection I would like to connect my unix to this one so I can=20
 > use the services such as irc, news, etc.
 > What do I need and what prgs?=20
 > How it is set up?
 > Do I need to connect using SLIP login to the other unix?
 > Is it possible using a shell instead SLIP?
 > 
 > Sal
 > 
 >   .------------------------------.                          -----.
 >  /__  Alias: SaL AciouS  ___     '--------------------------'     \
 >  |  `-------------------'  /      * JuSt mOrE ThAn A fRiEnD *      \
 >  |__  =A9 PX PRODUCTION =AE  _|-----------------------------------------|
 >     --------------------' |     Address: saausa@wurley.apana.org.au |
 >                            -----------------------------------------'
 > 

Andrew S. Clapp                                                 Sedona Internet
Systems Administrator                                         andrew@sedona.net