Setup PPTP server in Ubuntu

It's quick and easy. The steps are:

1. apt-get install pptpd
2. Modify "localip" and "remoteip" in /etc/pptpd.conf
3. (Optional) Modify "ms-dns" in /etc/ppp/pptpd-options
4. Add user accounts and passwords into /etc/ppp/chap-secrets. Place each user in a single line: username * "password" *

That's it.