Re: Use 2 modules to auth together.

26 Nov 2018

      Thank, Alan, you enlighten me.

Turns out  NAS( my VPN) does not support Access-Challenge.  Googled and
found  that Challenge seems to be a speical access-request  packet with the
Code field set to 11. So can I make the conclusion that  it would send an
access-quest again?  in other words, start a new authentication process
like another normal request with an exception that State attribute exists.

Let me suppose my VPN supports Access-Challenge, so my configuation is
something like:
-------------------------------

authorize {
      # The first auth does not have any State attribute.
      if (!State) {
                # MS-CHAP has no User-Password, so it's true.
                if (!User-Password )  {
                        # If !State and User-Password is null, then
goes to MS-CHAP:
                        update  {
                                &control:Auth-Type := MS-CHAP
                        }
                }

              else { reject }

      # Make sure it does not contain any other attributes except State.

     else {

            update {

             # IS THIS PART CORRECT ? I think so, as a new request is
issued by challage, so it would start over from top to buttom to walk
throught the entire process.

                &control:Auth-Type := MY_OWN_OTP_AUTH

               }
      }

}

authentication {

      Auth-Type MS-CHAP {
               mschap
               if (ok) {
                       update reply {
                               # Create a random State attribute:
                               State := "%{randstr:XXXXXXXXXXXXX}"
                               Reply-Message := "Please type your OTP:"
                       }
                       # Return Access-Challenge, goes to the 2nd auth.

                       # IS IT the correct way to raise a challange?
                       challenge

}

 Please help me to take a look at  configuration above, two questions:

1. Is else part correct?  which will use my own python auth module
2. Is it correct to raise a challenge using 'challenge' filter of
FreeRADIUS?

Thanks again.

On Mon, Nov 26, 2018 at 8:10 PM Alan DeKok <aland@deployingradius.com>
wrote:
...
On Nov 26, 2018, at 2:42 AM, luckydog xf <luckydogxf@gmail.com> wrote:
...
Our user is in AD and VPN will do an MSCHAP authentication first and
filter property of  User-Name from access request,  then call an
access-challenge to verify against  the other module whose logic is as
simple as starting a http request via http://XXX/check/username=
<http://xxx/check/username=><USER-NAME>&OTP=<xxxxxx>, if return 200,
it's
ok.
That's really just more authorization.
...
Basically, I want to auth a single login against two modules, only both
of them are successful, the auth could be deemed as OK.
That's possible, subject to certain caveats.
...
# ### authentication #####
authentication {
      Auth-Type MS-CHAP {
               mschap
               if (ok) {
                       update reply {
                               # Create a random State attribute:
                               State := "%{randstr:XXXXXXXXXXXXX}"
                               Reply-Message := "Please type your OTP:"
                       }
                       # Return Access-Challenge, goes to the 2nd auth.
                       challenge
That's good, but it likely won't work due to the NAS.  Doing OTP like
that requires support from the NAS.  Does the NAS support doing MS-CHAP and
then receiving an Access-Challenge?
If it does, then your next step is to write down what you want to
happen, like this:
1) packet 1 contains MS-CHAP
2) it authenticates agains MS-CHAP
3) if MS-CHAP is successful, it returns a State, challenge, and reply
message
4) when the next packet comes in with a state attribute, authenticate the
OTP
Note that the packet in step 4 *should not* contain any MS-CHAP
attributes.  It should just contain the response to the OTP.
So your freeradius configuration is:
1) run MS-CHAP like normal
2) do state / reply-message / challenge in "Auth-Type MS-CHAP"
As a *separate* item:
3) if packet contains State
4) do OTP verification
The only thing tying the two packets together is the State attribute.
They are otherwise completely independent.
Alan DeKok.
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