The CLI way
There are 3 files involved “/etc/ppp/peers/provider”, “/etc/chatscripts/pap” and “/etc/ppp/chap-secrets”.
connect "/usr/sbin/chat -v -f /etc/chatscripts/pap -T *99#"
# Serial device to which the modem is connected.
# Try to get the name server addresses from the ISP.
# Use this connection as the default route.
# Makes pppd "dial again" when the connection is lost.
# no compression - ppp is used only until the modem
ABORT "NO CARRIER"
ABORT "NO DIALTONE"
ABORT "NO DIAL TONE"
# Secrets for authentication using CHAP
# client server secret IP addresses
3ireland * 3ireland
The most important setting is for the APN in the chat script “3internet”, change this to suit your own provider. You may also need to change usernames and passwords. Until you are confident the connection is working correctly you may also want to enable debugging by uncommenting “#debug” in /etc/ppp/peers/provider. Commonly with 3 the DNS servers don’t get doled out correctly so it may be wise to comment “usepeerdns” and put the DNS servers for your connection into “/etc/resolv.conf” manually.
To start the connection simply type “pon”, to stop conversely “poff”. To start the connection on boot add “pon” to “/etc/rc.local”. To share the connection enable ip forwarding in “/etc/sysctl.conf” and have iptables configured correctly. See http://www.johnlewis.ie/the-importance-of-a-minimal-firewall/ for more information on the firewall side.