Resolveu o problema editando: /etc/ppp/pptpd-options
# Encryption (comment other options in this section!) require-mschap-v2 require-mppe-128 ms-dns 8.8.8.8 ms-dns 8.8.4.4
service pptpd restart
Estou tentando configurar uma VPN usando PPTP e conectar usando o iPhone (iOS), mas ela falha.
May 25 22:43:38 zork pptpd[28793]: CTRL: Client x.x.x.x control connection finished May 25 22:44:02 zork pptpd[28810]: MGR: connections limit (100) reached, extra IP addresses ignored May 25 22:44:02 zork pptpd[28811]: MGR: Manager process started May 25 22:44:02 zork pptpd[28811]: MGR: Maximum of 100 connections available May 25 22:44:08 zork pptpd[28812]: CTRL: Client x.x.x.x control connection started May 25 22:44:09 zork pptpd[28812]: CTRL: Starting call (launching pppd, opening GRE) May 25 22:44:09 zork pppd[28813]: Plugin /usr/lib/pptpd/pptpd-logwtmp.so loaded. May 25 22:44:09 zork pppd[28813]: pppd 2.4.5 started by root, uid 0 May 25 22:44:09 zork pppd[28813]: Using interface ppp0 May 25 22:44:09 zork pppd[28813]: Connect: ppp0 /dev/pts/5 May 25 22:44:09 zork pptpd[28812]: GRE: Bad checksum from pppd.
Resolveu o problema editando: /etc/ppp/pptpd-options
# Encryption (comment other options in this section!) require-mschap-v2 require-mppe-128 ms-dns 8.8.8.8 ms-dns 8.8.4.4
service pptpd restart