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sincas
Level 7
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Message 1 of 4

PPTP GRE Error=5 from Windows 7 machine

Hi,

Have seen a few issues lately with Windows 7 machines attempting to make a PPTP connection SG310 with firmware 3.2.2

The error message is as follows

Feb 15 13:14:13 pppd[23404]: LCP: timeout sending Config-Requests  
Feb 15 13:14:13 pppd[23404]: Connection terminated.
Feb 15 13:14:13 pppd[23404]: Exit.
Feb 15 13:14:13 pptpd[23403]: GRE: read(fd=6,buffer=145e4,len=4096) from PTY failed: status = -1 error = Error 5
Feb 15 13:14:13 pptpd[23403]: CTRL: PTY read or GRE write failed (pty,gre)=(6,7)
Feb 15 13:14:13 pptpd[23403]: CTRL: Client 114.75.53.150 control connection finished
Feb 15 13:14:13 pptpd[23403]: CTRL: Couldn't write packet to client.
Feb 15 13:14:15 last message repeated 1 time(s)

I remember there being a similar issue a few years ago.
You had to enter an extra command in the Custom Firewall Rules to ignore some request from the connecting VPN client.
The customer is using a 3G dongle which I suspect is now doing some internal NAT which is causing the problem.

It has been working fine for the past couple of weeks. Guessing something has changed at the Optus end.

Mark

3 Replies
rcamm
Level 13
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Message 2 of 4

Re: PPTP GRE Error=5 from Windows 7 machine

GRE packets are being blocked or incorrectly NATed

Most commonly it is a NAT issue

The UTM device does PPTP NAT correctly if used to pass through PPTP

sincas
Level 7
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Message 3 of 4

Re: PPTP GRE Error=5 from Windows 7 machine

Ross,

I know it is a NAT issue with the client device end.

I remember there being some iptables command we

could enter on the SG device to get it past this

LCP timeout issue.

This was back in the days when the product was

owned by Snapgear or Secure Computing.

Mark

rcamm
Level 13
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Message 4 of 4

Re: PPTP GRE Error=5 from Windows 7 machine

Back in the very early days there was an issue on the Snapgear, and you may be referring to this.

this problem has not occured in the last 8 years or so.

Since then the issues refers to incorrect NAT.

see knowledge base article KB62307 for the details on the NAT issue