It can also be used as a poor man's firewall to determine which services and systems get through, if the system is acting as a router. I plan mostly to telnet, ftp, and Web browse through the port, and there was some sort of UDP-based service that was automatically bringing up the connection several times an hour. I decided it was easier to nip this in the bud than to figure out what was actually bringing up the connection. I told it not to keep the link up for domain services. Apparently, the Sun was checking with the NeoSoft name servers to see how the weather was over at St. James Place and the link was staying up indefinitely because of these frequent messages.
Auto makes pppd run as a daemon.
I originally had this time set to 300 seconds, but sometimes I spend more than 5 minutes reading a Web page, and the kids seem to spill something or violently assault each other only after I'm in the middle of something. Of course, you have to do this before you need it, but it doesn't tie up a modem for so long when you've finished, if you kill the ping. This is the secret code that tells the answering pppd to assign a dynamic address. The tildes following the system names on each side of the colon tell the MST-PPP daemon that these IP addresses will change when the link is established. A very important option is noprotcomp.