title: VPN PPTP - CTRL: PTY read or GRE write failed
body: <p>I build my VPN server on digitocean using this script <a href="https://raw2.github.com/suyan/Scripts/master/Setup/pptp.sh" rel="nofollow">https://raw2.github.com/suyan/Scripts/master/Setup/pptp.sh</a></p>
  
  <p>However I cannot connect to this VPN server using either my iPhone or Mac. Here is <code>/var/log/syslog</code> says:</p>
  
  <pre><code>Oct 31 18:44:29 VPN pptpd[1422]: CTRL: Client xx.xx.xx.xx control connection started
  Oct 31 18:44:29 VPN pptpd[1422]: CTRL: Starting call (launching pppd, opening GRE)
  Oct 31 18:44:29 VPN pppd[1423]: Plugin /usr/lib/pptpd/pptpd-logwtmp.so loaded.
  Oct 31 18:44:29 VPN pppd[1423]: pppd 2.4.5 started by root, uid 0
  Oct 31 18:44:29 VPN pppd[1423]: Using interface ppp0
  Oct 31 18:44:29 VPN pppd[1423]: Connect: ppp0 &lt;--&gt; /dev/pts/1
  Oct 31 18:44:59 VPN pppd[1423]: LCP: timeout sending Config-Requests
  Oct 31 18:44:59 VPN pppd[1423]: Connection terminated.
  Oct 31 18:44:59 VPN pppd[1423]: Modem hangup
  Oct 31 18:44:59 VPN pppd[1423]: Exit.
  Oct 31 18:44:59 VPN pptpd[1422]: GRE: read(fd=6,buffer=b77c8480,len=8196) from PTY failed: status = -1 error = Input/output error, usually caused by unexpected termination of pppd, check option syntax and pppd logs
  Oct 31 18:44:59 VPN pptpd[1422]: CTRL: PTY read or GRE write failed (pty,gre)=(6,7)
  Oct 31 18:44:59 VPN pptpd[1422]: CTRL: Reaping child PPP[1423]
  Oct 31 18:44:59 VPN pptpd[1422]: CTRL: Client xx.xx.xx.xx control connection finished
  </code></pre>
  
  <p>Can anyone help?</p>