get the source and compile it on your 2.1.5.
I don't know where i got it from, but Brian Sommers should be listening
on this list.
I just grabbed the sources and compiled and installed them.
It runs perfect for me on my 2.1.5.
If you are not able to build from the sources, i sent you my binaries in
private email as tar.gz attachment.
ppp and pppctl go into /usr/sbin the manpages into /usr/share/man/man8
I've also included the source-tar-ball i grabed. Its not the newest one
(i think from 15.12.97).
Brian ... could you point holger to the latest sources of user-ppp ?