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Chapter 9There are various tags in the configuration file that are identified with a trailing ":"character. Each of these tags specifies an entry in the configuration file. The aboveexample has two tags—default and myisp.The ppp(8) utility always reads the default tag upon start up, so the global defaultsettings should be placed under this tag.As you noticed, there are a few dial-up related settings under this tag which specifydifferent logging options, serial port device (in this case /dev/cuad1, which isequivalent to COM2), serial line communication speed, and finally the dialing string.The first serial port (COM1) is identified as /dev/cuad0 and COM2 isidentified as /dev/cuad2.These settings would be working fine on a simple dial-up scenario in which youshould specify your modem port, based on your hardware configuration.Note that these configurations are specified under the default tag, which is used forany specific connection that you may want to use. If, for any reason, you want to usea specific serial port or dial string in different connection entries, you should movethese lines under the appropriate tags.As mentioned earlier, each connection is defined under its own entry that isidentified by a name. In the previous example, myisp tag contains specificconfiguration for an ISP, such as the dialing number, username, password, defaultgateway setting, and static interface IP address, if applicable. This is a simplescenario that you may use to connect to another host using a dial-up modem.There are seven different ways in which you can use ppp(8) to establish a PPPconnection, each specified by a command line option. The option name and itsdescription are listed in the following table:Option-auto-background-foreground-directDescriptionThe Dial-on-demand mode. The ppp(8) utility goes to backgroundand establishes connection upon detecting outgoing traffic on thetun interface.Establishes the connection and then goes to into the background,once the connection is up.Establishes the connection and stays in the foreground.Uses STDIN and STDOUT instead of network interface. This methodis useful while running PPP over TCP/UDP for tunneling.[ 147 ]