Digital Ocean Firewall Prevents PPTPD Connections

Posted October 16, 2017 3.7k views
FirewallVPNUbuntu 16.04

After implementing a cloud firewall using Digital Ocean Firewall (DOF) console, my pptpd server will no longer connect to clients. As soon as the DOF is unassigned from the droplet the pptpd service connects perfectly.

I am connecting from a Win 10 machine over pptpd with a user name and password.

There seems to be an error thrown when I call service pptpd status

pptpd[2074]: GRE: read(fd=6,buffer=611660,len=8196) from PTY failed: status = -1 error = Input/output error, usually caused by unexpected termination of pppd, check
[2074]: CTRL: PTY read or GRE write failed (pty,gre)=(6,7)

I’ve also tried opening port 1723 on both TCP / UDP incoming and outgoing to no avail
Custom TCP 1723 All IPv4 All IPv6

What I assume is happening is that the cloud firewall is taking over the IPTABLE rules which allows pptpd to allow the connection through.

These answers are provided by our Community. If you find them useful, show some love by clicking the heart. If you run into issues leave a comment, or add your own answer to help others.

Submit an Answer
2 answers

Have you opened port 47 (for GRE protocol)?

Yes 47 is open on both inbound and outbound but on TCP, is that correct?