[plug] PPP on demand

[Colin Rothnie]

I have had a lot of luck with diald.  I especially like the "filter" rules
where you can specify which type of packet brings up the link.  It is
therefore very easy for the diald box to ignore DNS, e-mail and netbios
packets but then bring up the link as soon as a http request is made.

One of the nifty things you can do with diald is communicate with the
process via a "fifo".  This special file allows you to "echo" commands
directly to the running daemon such as "echo force>/etc/diald/diald.fifo"
(keep the link up until "unforced" or "blocked"), "block" (keep the link
down until "unblocked") etc.  It is relatively trivial to create a web page
with simple CGI scripts to control the link.  This can be useful if your
linux gateway running diald doesn't have a screen.

There were "compatibility" problems with diald and RedHat 6.0.  The init
scripts and the version of PPP that came with RedHat caused routing problems
for diald.  I think these may have been fixed with 6.1, but in any case you
can download the updated packages for both the init scripts and PPP from
RedHat.  (There is a mailing list for diald, but they no longer answer
questions regarding default routes & RedHat.)

If you have RedHat, the best place to get diald is as a package from the
"contrib" area on their ftp server or mirrors.  I think there is a
diald-config package (or something similar) that simplifies configuration.

Cheers