Problema PPTP VPN

Question

Estou usando o sistema operacional Debian com pptpd . Meus clientes (Windows e Mac) não podem concluir a conexão.

O seguinte mostra no syslog:

Jun  2 12:52:37 vpn pptpd[891]: MGR: Maximum of 6 connections available
Jun  2 12:52:48 vpn pptpd[892]: MGR: Launching /usr/sbin/pptpctrl to handle client
Jun  2 12:52:48 vpn pptpd[892]: CTRL: local address = 192.168.30.91
Jun  2 12:52:48 vpn pptpd[892]: CTRL: remote address = 192.168.30.50
Jun  2 12:52:48 vpn pptpd[892]: CTRL: pppd options file = /etc/ppp/pptpd-options
Jun  2 12:52:48 vpn pptpd[892]: CTRL: Client 192.168.28.154 control connection started
Jun  2 12:52:48 vpn pptpd[892]: CTRL: Received PPTP Control Message (type: 1)
Jun  2 12:52:48 vpn pptpd[892]: CTRL: Made a START CTRL CONN RPLY packet
Jun  2 12:52:48 vpn pptpd[892]: CTRL: I wrote 156 bytes to the client.
Jun  2 12:52:48 vpn pptpd[892]: CTRL: Sent packet to client
Jun  2 12:52:48 vpn pptpd[892]: CTRL: Received PPTP Control Message (type: 7)
Jun  2 12:52:48 vpn pptpd[892]: CTRL: Set parameters to 100000000 maxbps, 64 window size
Jun  2 12:52:48 vpn pptpd[892]: CTRL: Made a OUT CALL RPLY packet
Jun  2 12:52:48 vpn pptpd[892]: CTRL: Starting call (launching pppd, opening GRE)
Jun  2 12:52:48 vpn pptpd[892]: CTRL: pty_fd = 6
Jun  2 12:52:48 vpn pptpd[892]: CTRL: tty_fd = 7
Jun  2 12:52:48 vpn pptpd[892]: CTRL: I wrote 32 bytes to the client.
Jun  2 12:52:48 vpn pptpd[892]: CTRL: Sent packet to client
Jun  2 12:52:48 vpn pptpd[893]: CTRL (PPPD Launcher): program binary = /usr/sbin/pppd
Jun  2 12:52:48 vpn pptpd[893]: CTRL (PPPD Launcher): local address = 192.168.30.91
Jun  2 12:52:48 vpn pptpd[893]: CTRL (PPPD Launcher): remote address = 192.168.30.50
Jun  2 12:52:48 vpn pppd[893]: Plugin /usr/lib/pptpd/pptpd-logwtmp.so loaded.
Jun  2 12:52:48 vpn pppd[893]: pppd 2.4.5 started by root, uid 0
Jun  2 12:52:48 vpn pppd[893]: Using interface ppp0
Jun  2 12:52:48 vpn pppd[893]: Connect: ppp0 <--> /dev/pts/1
Jun  2 12:52:48 vpn pptpd[892]: GRE: Bad checksum from pppd.
Jun  2 12:52:48 vpn pptpd[892]: CTRL: Received PPTP Control Message (type: 15)
Jun  2 12:52:48 vpn pptpd[892]: CTRL: Got a SET LINK INFO packet with standard ACCMs
Jun  2 12:52:48 vpn pptpd[892]: GRE: accepting packet #1
Jun  2 12:52:51 vpn pptpd[892]: GRE: accepting packet #2
Jun  2 12:52:54 vpn pptpd[892]: GRE: accepting packet #3
Jun  2 12:52:57 vpn pptpd[892]: GRE: accepting packet #4
Jun  2 12:53:00 vpn pptpd[892]: GRE: accepting packet #5
Jun  2 12:53:03 vpn pptpd[892]: GRE: accepting packet #6
Jun  2 12:53:06 vpn pptpd[892]: GRE: accepting packet #7
Jun  2 12:53:09 vpn pptpd[892]: GRE: accepting packet #8
Jun  2 12:53:12 vpn pptpd[892]: GRE: accepting packet #9
Jun  2 12:53:15 vpn pptpd[892]: GRE: accepting packet #10
Jun  2 12:53:18 vpn pppd[893]: LCP: timeout sending Config-Requests
Jun  2 12:53:18 vpn pptpd[892]: GRE: read(fd=6,buffer=610d20,len=8196) from PTY failed: status = -1 error = Input/output error, usually caused by unexpected termination of pppd, check option syntax and pppd logs
Jun  2 12:53:18 vpn pptpd[892]: CTRL: PTY read or GRE write failed (pty,gre)=(6,7)
Jun  2 12:53:18 vpn pptpd[892]: CTRL: Reaping child PPP[893]
Jun  2 12:53:18 vpn pptpd[892]: CTRL: Client 192.168.28.154 control connection finished
Jun  2 12:53:18 vpn pptpd[892]: CTRL: Exiting now
Jun  2 12:53:18 vpn pptpd[891]: MGR: Reaped child 892

Aqui está o meu arquivo pptpd-options:

refuse-pap
refuse-chap
refuse-mschap
require-mschap-v2
require-mppe-128
proxyarp
nodefaultroute
lock
nobsdcomp
noipx
#mtu 1490
#mru 1490

Quando vejo a atividade da interface ppp0 que vem da conexão, não vejo nenhuma atividade.

Por favor avise. Obrigado!

    

Answer 1

Isso pode ser um problema de firewall. Verifique se você está permitindo o tráfego correto no seu servidor VPN, especificamente, você precisa permitir TCP 1723 e Protocol 47 (GRE) antes que PPTP funcione corretamente. O problema que você vê no seu log pode ser causado por GRE não ser retransmitido corretamente do seu firewall.

Você também pode precisar adicionar mppe-stateful ao seu arquivo pptpd-options para permitir hosts do Windows. Dependendo de quantos roteadores NAT intermediários suas conexões podem passar, você precisará reduzir as configurações mru e mtu .

    

Answer 2

Alterando /etc/ppp/pptpd-options para as seguintes opções trabalhadas para mim:

refuse-pap
refuse-chap
refuse-mschap
#require-chap
#require-mschap
#require-mschap-v2
#require-mppe-128
mppe-stateful