PiePants is a PPTP client for Mac OS X. It supports encrypted communications for secure connections to your PPTP VPN. PiePants only supports a single PPTP connection at a time.
PiePants consists of four main pieces, though you normally only interact with one of them. The main piece is the user interface that you see when you start up the program. Bundled inside the program is a tool for bringing up and running a PPTP control channel (this program is called pptp). Also bundled inside is a user-mode PPP stack program called ppp (this program is a modified version of the same PPP stack used in FreeBSD). Finally, the program includes a tunnel-type device driver that is used to bring up the IP stack in the kernel.
Because several of these programs require access to protected resources, many of them must be run as root. The first time you run PiePants, the program will prompt you to repair the installation because it needs to enable the security settings for these components. The pptp program must execute with privileges because it uses a SOCK_RAW socket for the GRE tunnel portion of PPTP, and because it loads and unloads the pptp device driver. The ppp program must run with privileges because it modifies the routing table.
Each of these pieces communicates together to provide a PPTP tunnel to your network.