https://forum.howtoforge.com/threads/setting-up-ppp-chap-authentication-on-a-vpn-server.40539/
setting up PPP CHAP authentication on a VPN server | Howtoforge - Linux Howtos and Tutorials
im trying to set up a VPN server on CentOS 5.3 so far i have got OpenSwan working for IPsec and xl2tpd running with PPP CHAP authentication. the...
setting up pppon avpn serverchapauthentication