Centos – VPN error 619 – “A connection to the remote computer could not be established.”

centospptpvpn

Have been trying to get this PPTP VPN working on a CentOS 6 x64 VPS for a few days but im getting:

"Error 619 – A connection to the remote computer could not be established."

I did research on Google and most of the time it was due to routers not allowing VPN passthrough or whatnot, however I have another CentOS VPS setup exactly the same (used the same guide to set it up) and it works perfectly..

I did find some error messages in the "/var/log/messages" log that I looked up on Google but couldn't find any results on how to fix it. Hopefully someone else could help me out with this.

Mar 8 20:14:50 direct pppd[1507]: pppd 2.4.5 started by root, uid 0
Mar 8 20:14:50 direct pppd[1507]: Using interface ppp0
Mar 8 20:14:50 direct pppd[1507]: Connect: ppp0 <–> /dev/pts/1
Mar 8 20:15:20 direct pppd[1507]: LCP: timeout sending Config-Requests
Mar 8 20:15:20 direct pppd[1507]: Connection terminated.
Mar 8 20:15:20 direct pppd[1507]: Modem hangup
Mar 8 20:15:20 direct pppd[1507]: Exit.
Mar 8 20:15:20 direct pptpd[1506]: GRE: read(fd=6,buffer=611860,len=8196) from PTY failed: status = -1 error = Input/output error, usually caused by unexpected termination of pppd, check option syntax and pppd logs
Mar 8 20:15:20 direct pptpd[1506]: CTRL: PTY read or GRE write failed (pty,gre)=(6,7)
Mar 8 20:15:20 direct pptpd[1506]: CTRL: Client 76.177.167.162 control connection finished

It seems to be working correctly up until "LCP: timeout sending Config-Requests"

Best Answer

As indicated in the logs, the GRE tunnel cannot be established.

Maybe your ISP filters ip traffic and let udp + tcp + icmp go throught, but not gre (ie the "vpn passthrough" feature ).

Another problem with GRE is it does not go well with NAT. For example, if you have two clients behind the same nat-ed ip address which connect to the same remote server, there are chances that only one of them will succeed in establishing the gre tunnel with the server.

At last if your vps is running on OpenVZ for example, its kernel is shared with the hypervisor, and maybe the gre module is not available. Try modprobe ip_gre then lsmod | grep gre in order to check the gre module is available in your kernel.

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