PPP-2.4.4

Warning

Instructions in this section result in your password appearing on the screen in a visible clear-text form. Make sure that nobody else looks at the screen.

Passwords are stored in /etc/ppp/pap-secrets and /etc/ppp/chap-secrets files, depending on the authentication method used by the ISP. If in doubt, place the password into both files. E.g., if the username given by the ISP is “jdoe”, the password is “guessit”, the ISP uses PAP and the user wants to name this account “dialup” in order to distinguish it from other PPP accounts, the following file has to be created:

touch /etc/ppp/pap-secrets
chmod 600 /etc/ppp/pap-secrets
cat >>/etc/ppp/pap-secrets <<"EOF"
# username      remotename    password        IP for the peer
jdoe            dialup        guessit         *
EOF

If you don't run your own caching DNS server, create a simple ip-up script (to be called by pppd automatically once the connection is brought up) that populates the /etc/resolv.conf file with nameservers specified by the ISP.

cat >/etc/ppp/ip-up <<"EOF"
#!/bin/sh
if [ "$USEPEERDNS" = "1" ] && [ -s /etc/ppp/resolv.conf ]
then
        install -m 644 /etc/ppp/resolv.conf /etc/resolv.conf
fi
EOF
chmod 755 /etc/ppp/ip-up

If you use a caching DNS server such as BIND-9.4.1-P1 or Pdnsd, the script above is wrong for you. In such case, write your own script that tells your caching nameserver to forward queries to upstream DNS servers specified in the $DNS1 and $DNS2 environment variables.

Dialup connections are established with the help of a modem connected to a computer and the telephone line. The modem dials a telephone number of the ISP's modem, and they exchange data using the signal frequencies 300-4000 Hz. Typical data transfer rate is 40-50 kilobits per second, and the gateway ping time (latency) is up to 300-400 ms. In order to configure the dialup connection, it is required to know the telephone number of the ISP's modem pool, the username and the password.

In order to configure a dialup connection, two files have to be created: a chat script that automates the connection procedure (common for all dialup accounts), and a peer file that provides configuration information about a specific connection to pppd:

cat >/etc/ppp/dialup.chat <<"EOF"
ABORT BUSY ABORT 'NO CARRIER' ABORT VOICE ABORT 'NO DIALTONE'
ABORT 'NO DIAL TONE' ABORT 'NO ANSWER' ABORT DELAYED
ABORT ERROR ABORT BLACKLISTED

TIMEOUT 5
'' AT
# \T is the phone number, passed from /etc/ppp/peers/dialup
OK-+++\dATH0-OK ATD\T
TIMEOUT 75
CONNECT \d\c
EOF

cat >/etc/ppp/peers/dialup <<"EOF"
# Your username at the ISP
user "jdoe"
# What should be in the second column in /etc/ppp/*-secrets
remotename "dialup"
# Replace TTTTTTT with the ISP phone number
connect "/usr/sbin/chat -T TTTTTTT -f /etc/ppp/dialup.chat"

# Specify your modem serial port and speed below
/dev/ttyS0
115200

# The settings below usually don't need to be changed
updetach
noauth
hide-password
debug
lock
defaultroute
noipdefault
usepeerdns
EOF

The first three lines of the /etc/ppp/dialup.chat file abort the script when it receives an indication of an error from the modem. Then the timeout is set to 5 seconds and the script checks that the modem responds to the dummy AT command at all. If not, measures are taken to dewedge it (by interrupting the data transfer and going on hook). Then the telephone number is dialed, and the script waits for the answer for 75 seconds. The serial connection is considered established when the modem sends the string CONNECT.

GPRS and EDGE connections are established with the help of a cellular phone connected to a computer via serial or USB cable, or using Bluetooth. The phone exchanges data packets with the nearest base station, which can be up to 35 kilometers away. The maximum possible data transfer rate is 170 kilobits per second for GPRS and 474 kilobits per second for EDGE, but many cellular operators impose lower limits, such as 64 kilobits per second. The gateway ping time is 900 ms for GPRS, which makes playing many online games impossible and causes connection to ICQ to be unreliable. In order to configure a GPRS or EDGE connection, it is required to know the access point name (APN) and, rarely, the username and the password. In most cases, billing is based on the telephone number, and the username/password pair is not needed, as assumed in the example below.

In order to configure a GPRS connection, two files have to be created: a chat script that automates the connection procedure (common for all GPRS accounts), and a peer file that provides configuration information about a specific connection to pppd:

cat >/etc/ppp/gprs.chat <<"EOF"
ABORT BUSY ABORT 'NO CARRIER' ABORT VOICE ABORT 'NO DIALTONE'
ABORT 'NO DIAL TONE' ABORT 'NO ANSWER' ABORT DELAYED
ABORT ERROR ABORT BLACKLISTED

TIMEOUT 5
'' AT
OK-+++\dATH0-OK ATZ
# \T is the APN, passed from /etc/ppp/peers/gprs
# This example stores the APN as profile #1 in the phone.
# The "telephone number", *99***<profile_number>#, is always the same.
# If you want to store this as profile #2, change 1 to 2 in the
# following two lines.
OK AT+CGDCONT=1,"IP","\T"
OK "ATD*99***1#"
CONNECT \d\c
EOF

cat >/etc/ppp/peers/gprs <<"EOF"
# Replace inet.example.com with the proper APN for your provider
connect "/usr/sbin/chat -T inet.example.com -f /etc/ppp/gprs.chat"

# Specify your cellphone serial port and speed below
# Note: you must manually send some vendor-specific AT commands
# to certain old cellular phones (such as Sony-Ericsson T200)
# in order to achieve connection speed more than 9600 bits ber second.
/dev/ttyS1
115200

# The settings below usually don't need to be changed
noccp
noauth
updetach
debug
lock
defaultroute
noipdefault
usepeerdns
EOF

PPPoE connections are established over Ethernet, typically between a computer and an ADSL router (usually installed in the same room) that forwards the packets down the telephone line using frequencies 25-2500 kHz, thus not interfering with voice calls. Although the router can, in theory, forward any Ethernet packet, PPP encapsulation is used for password-based authentication, so that the ISP can limit the bandwidth and charge money according to the chosen tariff. The maximum data transfer rate on ADSL is 24 megabits per second, and the gateway ping time is typically less than 10 ms. In order to configure a PPPoE connection, it is required to know the username, the password, and, sometimes, the service name and/or the access concentrator name.

In order to configure a PPPoE connection, only the peer file has to be created:

cat >/etc/ppp/peers/adsl <<"EOF"
plugin rp-pppoe.so
# Ethernet interface name
eth0
# Your username at the ISP
user "jdoe"
# What should be in the second column in /etc/ppp/*-secrets
remotename "adsl"
# If needed, specify the service and the access concentrator name
# rp_pppoe_service "internet"
# rp_pppoe_ac "ac1"

# The settings below usually don't need to be changed
noauth
hide-password
updetach
debug
defaultroute
noipdefault
usepeerdns
EOF

In order to establish a PPP connection described by the /etc/ppp/peers/peername file, run, as root or as a member of the pppusers group:

pon peername

In order to tear the connection down, run:

poff peername

If your service provider does not charge by the minute, it is usually good to have a bootscript handle the connection for you. You can, of course, choose not to install the following script, and start your connection manually with the pon command, as described above. If you wish your PPPoE connection to be brought up at boot time, run:

make install-service-pppoe

The above command installs the pppoe service script and the /etc/ppp/peers/pppoe file with some settings that make sense for most PPPoE connections. The bootscript calls pppd with the the following options:

pppd call pppoe ${1} linkname ${1} ${PPP_OPTS}

Here “${1}” is the network interface name, “linkname ${1}” is added for creation of the /var/run/ppp-${1}.pid file with the pppd process ID (to be used when bringing the connection down), and the “${PPP_OPTS}” variable contains user-specified options such as “user” and “remotename”.

Now create the config file for use with the pppoe service script:

install -v -d /etc/sysconfig/network-devices/ifconfig.eth0 &&
cat > /etc/sysconfig/network-devices/ifconfig.eth0/pppoe << "EOF"
ONBOOT="yes"
SERVICE="pppoe"
PPP_OPTS="user jdoe remotename adsl"
EOF

Note

Instead of specifying additional options in the $PPP_OPTS variable, you can also edit the /etc/ppp/peers/pppoe file, but then your configuration will be lost when upgrading BLFS bootscripts.