MS CHAP v2 with Linux

man pppd версии 2.4
EXAMPLES OF MICROSOFT EXTENSIONS
To authentificate client with Microsoft CHAP version 1 or
2, you need to use those options:
auth
+chap
+chapms
+chapms-v2

To make possible to authentificate itself with Microsoft
CHAP version 1 or 2, you need to add those options:
+chapms
+chapms-v2