Linux
PPTP VPN問題
我正在使用 Debian 作業系統
pptpd。我的客戶端（Windows 和 Mac）無法完成連接。syslog 中顯示以下內容：
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這是我的 pptpd 選項文件：
refuse-pap refuse-chap refuse-mschap require-mschap-v2 require-mppe-128 proxyarp nodefaultroute lock nobsdcomp noipx #mtu 1490 #mru 1490當我觀察連接時出現的 ppp0 介面的活動時，我根本看不到任何活動。
請指教。謝謝 ！
這可能是防火牆問題。檢查您是否允許正確的流量進入您的 VPN 伺服器，特別是您需要允許
TCP 1723並且Protocol 47 (GRE)之前PPTP將正常工作。您在日誌中看到的問題可能是由於GRE未從防火牆正確中繼造成的。您可能還需要添加
mppe-stateful到您的pptpd-options文件以允許 Windows 主機。根據您的連接可能通過多少個中間NAT路由器，您需要減少mru和mtu設置。