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I've followed this tutorial to build a VPN on EC2:

PPTP VPN on Amazon EC2

But when I run these steps, I always fail to connect to EC2 through VPN. Every time, the system confirms a connection, but eventually the system stops and reports a failure.

In the log: /var/log/messages, I can see:

pppd 2.4.5 started by ec2-user, uid 0
Using interface ppp0
Connect: ppp0 <--> /dev/pts/0
Modem hangup

I am confused on these items:

  • What kind of IP should I input to /etc/pptpd.conf? My IP domain is 192.168.0.xxx. I input 192.168.0.1 and 192.168.0.2-100 to /etc/pptpd.conf. Will this be a check point?
  • How to check if I have enabled port 1723 on EC2?

Can anybody give me some ideas on how to debug this case?

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  • another question is: what is the server name? should i take EC2 public DNS as vpn hostname? – skyworld Jun 25 '17 at 7:28
  • Is there a firewall and/or proxy on client or server side? – Ortomala Lokni Jun 25 '17 at 10:22
  • I use win10 and i have installed macfee to defend virus. But I'm sure it is ok because i can access other VPN servers. – skyworld Jun 25 '17 at 11:49
  • What about Amazon EC2 Security Groups? – Ortomala Lokni Jun 25 '17 at 11:55
  • i have set security group to enable all traffics from any port, but still fail – skyworld Jun 25 '17 at 13:20
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PPTP uses two different protocols, TCP port 1723 is used for initial setup, but the data streams use GRE -- Generic Route Encapsulation -- which is neither TCP nor UDP -- it's IP protocol number 47.

You need to create a security group rule to allow GRE traffic. This requires that your instance be in a VPC, since EC2 Classic security groups do not support a rule like this.

TCP 1723 seems to be open, or you wouldn't be seeing the log entries.

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    @skyworld Note also that macOS Sierra no longer support PPTP because of numerous security vulnerabilities, you should maybe consider using something more recent such as OpenVPN. – Ortomala Lokni Jun 25 '17 at 21:05
  • @OrtomalaLokni that is, unfortunately, a very good point. – Michael - sqlbot Jun 25 '17 at 23:24
  • Hi Michael, I'm not sure if this command is what you are discussing: "iptables -A INPUT -p gre -j ACCEPT", i have tried this command but still failed for login – skyworld Jun 26 '17 at 12:03
  • Hi Ortomala, thanks for your reminder. What i need now is just to build a VPN so that I can access google to search some documents. PPTP should be enough for me. – skyworld Jun 26 '17 at 12:05
  • @skyworld no. I'm referring to the EC2 security group that controls external access to your instance. – Michael - sqlbot Jun 26 '17 at 12:39

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