Software mentioned in this article can be found at the following locations:
tcl/tk/wish: The home of Tcl is https://sunscript.sun.com/ at Sun Microsystems. PPPui uses features that were introduced in tk4.2/tcl7.6—which are available at this site.
FVWM95: The home page is https://www.linux-kheops.com/pub/FVWM95/fvwm95.html, with dozens of mirrors around the world.
PPP utilities: The current version is at the Sunsite repository: https://sunsite.unc.edu/pub/Linux/system/network/serial/ppp/ppp-2.2.0g.tar.gz.
Other PPP GUIs: You'll find alternatives to the PPP utilities and to PPPui at the Sunsite repository: https://sunsite.unc.edu/pub/Linux/system/network/serial/ and https://sunsite.unc.edu/pub/Linux/system/network/serial/ppp/.
PPPui: The PPPui and rscript source is posted at https://www.teleport.com/~nmeyers/PPPui/ and ftp://ftp.ssc.com/pub/lj/listings/issue50/2491.tgz.