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I tried to setup a L2TP/IPsec VPN server with PSK authentication according to this tutorial on a Ubuntu server but there is a problem when I'm trying to connect to this server with a Windows 7 client. I can't connect using PSK however it works when I use certificate for authentication. I don't know why? Any idea?


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Windows 7 has some different settings from Windows XP which can affect compatibility; the most notable ones are the removed support for the MS-CHAP V1 authentication protocol (only MSCHAP V2 is supported) and different encryption settings for L2TP/IPSEC (as documented here).

I don't know how this applies to Ubuntu, but maybe it can point you in the right direction.

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Thanks. But MS-CHAP is completely disabled in my Windows 7 VPN client configuration and it's using CHAP protocol. – cartoonist Jul 7 '11 at 8:47
...why?!? CHAP is way more insecure... – Massimo Jul 7 '11 at 8:55
I think security is guaranteed by IPSec and L2TP key phrase. isn't it? – cartoonist Jul 30 '11 at 5:07

I had the same problem due to my IPSEC/L2TP server (Ubuntu 12.04 precise) and clients (Windows 7 and Windows XP) being behind NAT. This required a registry modification. After rebooting I was able to connect.

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