11.2.9. Dialup Interfaces
If you are connecting to the Internet via a dialup connection, a configuration file is necessary for the interface.
PPP interface files are named using the following format:
ifcfg-pppX- where X is a unique number corresponding to a specific interface.
The
PPP interface configuration file is created automatically when wvdial, or Kppp is used to create a dialup account. It is also possible to create and edit this file manually.
The following is a typical
/etc/sysconfig/network-scripts/ifcfg-ppp0 file:
DEVICE=ppp0 NAME=test WVDIALSECT=test MODEMPORT=/dev/modem LINESPEED=115200 PAPNAME=test USERCTL=true ONBOOT=no PERSIST=no DEFROUTE=yes PEERDNS=yes DEMAND=no IDLETIMEOUT=600
Serial Line Internet Protocol (SLIP) is another dialup interface, although it is used less frequently.
SLIP files have interface configuration file names such as ifcfg-sl0.
Other options that may be used in these files include:
-
DEFROUTE=answer - where answer is one of the following:
yes— Set this interface as the default route.no— Do not set this interface as the default route.
DEMAND=answer- where answer is one of the following:
yes— This interface allowspppdto initiate a connection when someone attempts to use it.no— A connection must be manually established for this interface.
IDLETIMEOUT=value- where value is the number of seconds of idle activity before the interface disconnects itself.
INITSTRING=string- where string is the initialization string passed to the modem device. This option is primarily used in conjunction with
SLIPinterfaces. LINESPEED=value- where value is the baud rate of the device. Possible standard values include
57600,38400,19200, and9600. MODEMPORT=device- where device is the name of the serial device that is used to establish the connection for the interface.
MTU=value- where value is the Maximum Transfer Unit (MTU) setting for the interface. The MTU refers to the largest number of bytes of data a frame can carry, not counting its header information. In some dialup situations, setting this to a value of
576results in fewer packets dropped and a slight improvement to the throughput for a connection. NAME=name- where name is the reference to the title given to a collection of dialup connection configurations.
PAPNAME=name- where name is the user name given during the Password Authentication Protocol (PAP) exchange that occurs to allow connections to a remote system.
PERSIST=answer- where answer is one of the following:
yes— This interface should be kept active at all times, even if deactivated after a modem hang up.no— This interface should not be kept active at all times.
REMIP=address- where address is the
IPaddress of the remote system. This is usually left unspecified. -
WVDIALSECT=name - where name associates this interface with a dialer configuration in
/etc/wvdial.conf. This file contains the phone number to be dialed and other important information for the interface.
