Linux PPP

Options file

This file contains options that govern PPP's connection negotiations.

It is stored in /etc/ppp/options.

    # /etc/ppp/options -*- sh -*- general options for pppd
    # created 16-Sep-1996

    connect "/usr/sbin/chat -v -f /etc/ppp/ppp.chat"
    crtscts
    debug
    defaultroute
    lock
    modem
    noipdefault

This file contains parameters that control pppd's negotiation with Enterprise's PPP server:

• connect This option takes a string argument, which is the command to be run to initialise the connection. I have it set up to run chat and to read its conversation from my chat script.
• crtcts Flow control to the modem is to be done by RTS/CTS hardware handshaking.
• debug It will send debugging messages to the syslog daemon.
• defaultroute Once the connection is up, PPP is to set it up as the default route for IP packets which are not for the local network. (When the PPP connection goes down, the default route is deleted automatically.)
• lock This option tells PPP to use a UUCP-style lock which prevents any other program (that uses the same lock) from trying to access the serial line.
• modem This option tells PPP to watch the modem control lines in the serial interface in order to see whether the serial connection is up or not.
• noipdefault We tell PPP not to try to work out the local IP address from /etc/hosts; it is to be supplied by the Enterprise server.

Note that we do not try to specify an IP address, because Enterprise assign addresses dynamically. (The DOS/Windows versions of PPP need to be told to use IP address 0.0.0.0, which allows dynamic address assignment, but Linux PPP does this automatically when no IP address is given.)