Just looked at this line in my config there is a "--ntresponse" instead of "#ntresponse" [mschap] expand: #ntresponse=%{mschap:NT-Response:-00} -> #ntresponse=f7b8cd66af90b5791fb4b09421dbbf2cbed180e7e72304b5 Exec-Program output: Logon failure (0xc000006d) Exec-Program-Wait: plaintext: Logon failure (0xc000006d) Tested on command line and getting this: ntlm_auth --request-nt-key --username=User001 --domain=SWMNT --challenge=6e374178999f1bb7 --nt-response=b1f6e77179f80d6cd0b9edf43747e08daa1e32bf732df419 NT_KEY: D939DA6BBE72DDD138696ECFCA691648 With # getting the same error like in the radtest: ntlm_auth --request-nt-key --username=User001 --domain=SWMNT --challenge=6e374178999f1bb7 #ntresponse=b1f6e77179f80d6cd0b9edf43747e08daa1e32bf732df419 Logon failure (0xc000006d) In my mschap module the ntresponse parameter is written with "--", so why is radtest interpreting it with an "#" ??