Unpack the checkpassword package:
gunzip checkpassword-0.90.tar
tar -xf checkpassword-0.90.tar
cd checkpassword-0.90
Compile the checkpassword program:
make
As root, install /bin/checkpassword:
make setup check
Finally, send me the portability notes created by the compilation process:
( echo 'First M. Last'; cat `cat SYSDEPS` ) \
| mail djb-sysdeps@cr.yp.to
Replace First M. Last with your name.
Simulate a failed POP login:
# /var/qmail/bin/qmail-popup blah /bin/checkpassword pwd
+OK <...@blah>
user Frodo
+OK
pass Friend
-ERR authorization failed
Simulate a successful POP login, using a correct account name and password instead of Frodo and Friend. You should see the account's home directory.
Simulate a successful POP login again, with id instead of pwd. You should see the account's uid and gid.