If you're trying to connect from a Mac to a Windows Server's VPN (PPTP), accepting only MS-CHAPv2, the client fails with the following error:
18/6/13 9:06:08.672 AM pppd: MS-CHAP authentication failed: E=691 Authentication failure
Proposed solutions (Post from Macworld, Post from Apple forum) are to disable the
Digitally sign communications (always) and enable it only
if client agrees (not tested, since we cannot change the settings on the server).
Often, you don't want to or can't change any setting on the server and thus look for a solution on the client side.
Has anyone found a command line to force the usage of MS-CHAPv2, or, in other words, to preclude the usage of any other authentication method?