Eu tive quase exatamente o mesmo problema e veja como resolvi o problema:
Ativei a criptografia de 128 bits com todas as outras opções ativadas.
Agora funciona! :)
Estou tentando configurar no Linux (Kubuntu 9.10) uma VPN que eu já uso do Windows.
Instalei o pacote network-manager-pptp e adicionei a VPN no Network Manager. Estes são os parâmetros no botão "avançado":
Quando tento conectar, não funciona e é isso que recebo no log do sistema:
2010-04-08 13:53:47 pcelena NetworkManager <info> Starting VPN service 'org.freedesktop.NetworkManager.pptp'...
2010-04-08 13:53:47 pcelena NetworkManager <info> VPN service 'org.freedesktop.NetworkManager.pptp' started (org.freedesktop.NetworkManager.pptp), PID 4931
2010-04-08 13:53:47 pcelena NetworkManager <info> VPN service 'org.freedesktop.NetworkManager.pptp' just appeared, activating connections
2010-04-08 13:53:47 pcelena pppd[4932] Plugin /usr/lib/pppd/2.4.5//nm-pptp-pppd-plugin.so loaded.
2010-04-08 13:53:47 pcelena NetworkManager <info> VPN plugin state changed: 3
2010-04-08 13:53:47 pcelena pppd[4932] pppd 2.4.5 started by root, uid 0
2010-04-08 13:53:47 pcelena NetworkManager <info> VPN connection 'MYVPN' (Connect) reply received.
2010-04-08 13:53:47 pcelena NetworkManager SCPlugin-Ifupdown: devices added (path: /sys/devices/virtual/net/ppp0, iface: ppp0)
2010-04-08 13:53:47 pcelena NetworkManager SCPlugin-Ifupdown: device added (path: /sys/devices/virtual/net/ppp0, iface: ppp0): no ifupdown configuration found.
2010-04-08 13:53:47 pcelena pppd[4932] Using interface ppp0
2010-04-08 13:53:47 pcelena pppd[4932] Connect: ppp0 <--> /dev/pts/2
2010-04-08 13:53:47 pcelena pptp[4934] nm-pptp-service-4931 log[main:pptp.c:314]: The synchronous pptp option is NOT activated
2010-04-08 13:53:47 pcelena pptp[4927] nm-pptp-service-4918 log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 7 'Outgoing-Call-Request'
2010-04-08 13:53:47 pcelena pptp[4927] nm-pptp-service-4918 log[ctrlp_disp:pptp_ctrl.c:858]: Received Outgoing Call Reply.
2010-04-08 13:53:47 pcelena pptp[4927] nm-pptp-service-4918 log[ctrlp_disp:pptp_ctrl.c:897]: Outgoing call established (call ID 1, peer's call ID 14800).
2010-04-08 13:53:48 pcelena pppd[4932] CHAP authentication succeeded
2010-04-08 13:53:48 pcelena pppd[4932] CHAP authentication succeeded
2010-04-08 13:53:48 pcelena pppd[4932] LCP terminated by peer
2010-04-08 13:53:48 pcelena pptp[4927] nm-pptp-service-4918 log[ctrlp_disp:pptp_ctrl.c:929]: Call disconnect notification received (call id 14800)
2010-04-08 13:53:48 pcelena pptp[4927] nm-pptp-service-4918 log[ctrlp_disp:pptp_ctrl.c:788]: Received Stop Control Connection Request.
2010-04-08 13:53:48 pcelena pptp[4927] nm-pptp-service-4918 log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 4 'Stop-Control-Connection-Reply'
2010-04-08 13:53:48 pcelena pptp[4927] nm-pptp-service-4918 log[callmgr_main:pptp_callmgr.c:258]: Closing connection (shutdown)
2010-04-08 13:53:48 pcelena pptp[4927] nm-pptp-service-4918 log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 12 'Call-Clear-Request'
2010-04-08 13:53:48 pcelena pptp[4927] nm-pptp-service-4918 log[callmgr_main:pptp_callmgr.c:258]: Closing connection (shutdown)
2010-04-08 13:53:48 pcelena pptp[4927] nm-pptp-service-4918 log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 12 'Call-Clear-Request'
2010-04-08 13:53:48 pcelena pptp[4927] nm-pptp-service-4918 log[call_callback:pptp_callmgr.c:79]: Closing connection (call state)
2010-04-08 13:53:48 pcelena pppd[4932] Modem hangup
2010-04-08 13:53:48 pcelena pppd[4932] Connection terminated.
2010-04-08 13:53:48 pcelena NetworkManager <info> VPN plugin failed: 1
2010-04-08 13:53:48 pcelena NetworkManager SCPlugin-Ifupdown: devices removed (path: /sys/devices/virtual/net/ppp0, iface: ppp0)
2010-04-08 13:53:48 pcelena pppd[4932] Exit.
2010-04-08 13:53:48 pcelena NetworkManager <info> VPN plugin failed: 1
2010-04-08 13:53:48 pcelena NetworkManager <info> VPN plugin state changed: 6
2010-04-08 13:53:48 pcelena NetworkManager <info> VPN plugin state change reason: 0
2010-04-08 13:53:48 pcelena NetworkManager <WARN> connection_state_changed(): Could not process the request because no VPN connection was active.
2010-04-08 13:53:48 pcelena NetworkManager <info> Policy set 'Auto eth0' (eth0) as default for routing and DNS.
2010-04-08 13:54:01 pcelena NetworkManager <debug> [1270727641.001390] ensure_killed(): waiting for vpn service pid 4931 to exit
2010-04-08 13:54:01 pcelena NetworkManager <debug> [1270727641.001479] ensure_killed(): vpn service pid 4931 cleaned up
O erro que se destaca aqui é " pppd [4932] LCP terminado por peer ".
Alguém tem sugestões sobre o que pode ser o problema e como fazê-lo funcionar?
Eu tive quase exatamente o mesmo problema e veja como resolvi o problema:
Ativei a criptografia de 128 bits com todas as outras opções ativadas.
Agora funciona! :)