Connecting to an external PPTP server from Mirotik Hotspot

RouterOS General
1

Dear All,

We use Router OS 5.19 as a hotspot for our public wireless network.

We recently noticed that we cannot connect to an external PPTP server from our hotspot system. Using the the built in client in Windows Machines (XP and 7), it failes while on the credential checking page. It seems to be a problem with handling GRE.

Is there any kind of fix for this?

Thanks.

2

Please make sure Windows host is authenticated at HotSpot, during PPTP session attempt.
Default HotSpot settings do not put any limitation or restrictions to PPTP.

3

Please make sure Windows host is authenticated at HotSpot, during PPTP session attempt.
Default HotSpot settings do not put any limitation or restrictions to PPTP.

Thanks for the quick reply.

I am 100% certain that my host is authenticated. I get the same result with any Windows or Linux computer I have got.
I can connect to the internet and everything works fine. But my outgoing PPTP connection fails.

If I connect my computer to a different network (home, corporate network) then the connection establishes without any problem.

When I tried to monitor the network traffic with Torch, to see where the problem is, I could not even make Torch monitoring GRE traffic in Winbox. On the terminal, the Torch command has an option to monitor GRE protocol, but it did not sow any packets reaching either interface of the hotspot.

I do not know, where the problem lies and I would appreciate any clue I could start on.

Thanks,

4

Make sure you do not have NAT router before HotSpot router.
MikroTik router has PPTP NAT matched enabled by default, perhaps NAT router after MikroTik does not have such option and it blocks PPTP connection.

You may try to run alternative L2TP/IPsec/OpenVPN.

5

Thank you for your response and I apologise for the late reply but we have been a little bit busy recently.

Make sure you do not have NAT router before HotSpot router.
MikroTik router has PPTP NAT matched enabled by default, perhaps NAT router after MikroTik does not have such option and it blocks PPTP connection.

Our hotspot’s external side is directly connected to the internet. We actually have a pool of public IP addresses to be issued to the hotspot client by DHCP. We do not have any device with NAT after our hotspot.

You may try to run alternative L2TP/IPsec/OpenVPN.

It is not not an option, as our customers want to access their office through PPTP, so we have no control over those systems.

Could you give me some idea, how I can monitor PPTP traffic on my Mikrotik box. I am asking this, as using torch, I could not see any GRE traffic on any of the hotspot’s interface.

Thanks again.