GroupStudy.com GroupStudy.com - A virtual community of network engineers
 Home  BookStore  StudyNotes  Links  Archives  StudyRooms  HelpWanted  Discounts  Login
Re: aaa authorization (last method) posted 11/04/2003
[Chronological Index] [Thread Index] [Top] [Date Prev][Date Next] [Thread Prev][Thread Next]


Dmitry,

I labbed up the scenarios described earlier, and the results I got were as
you suggest:

If you authenticate through any permitted AAA authentication method, then
the "if-authenticated" method will authorize, whether the AAA server is
reachable or not.

The only scenario I could find where this did not work was when I had NO AAA
authentication commands, but did have AAA authorization commands.  Here the
"if-authenticated" will fail.  When the AAA server is down, it still fails,
and adding the "none" method to the end does not help.

So, I have to agree that I see no case in which having both
"if-authenticated" and "none" in the same list makes sense.  One does see it
in legacy configs, maybe it is just superstition!

-Bob Sinclair
 CCIE #10427, CISSP, MCSE

----- Original Message ----- 
From: "Volkov Dmitry" <dmitry.volkov@xxxxxxxxxx>
To: "'Bob Sinclair'" <bsin@xxxxxxx>
Cc: <security@xxxxxxxxxxxxxx>; <ccielab@xxxxxxxxxxxxxx>
Sent: Monday, November 03, 2003 6:56 PM
Subject: RE: aaa authorization (last method)


> Bob, see inline
>
> > -----Original Message-----
> > From: Bob Sinclair [mailto:bsin@xxxxxxx]
> > Sent: Monday, November 03, 2003 6:32 PM
> > To: dmitry.volkov@xxxxxxxxxx; security@xxxxxxxxxxxxxx
> > Cc: ccielab@xxxxxxxxxxxxxx
> > Subject: Re: aaa authorization (last method)
> >
> >
> > Dmitry,
> >
> > It seems to me that in order to pass the "if-authenticated"
> > method, AAA
> > server needs to be reachable.
>
> Why ?? You ALREADY authenticated and "if-authenticated" will allow to
> authorize .
>
> > What if you successfully
> > authenticate and
> > then shut down the interface you would use to get to the AAA
> > server?  Would
> > you be able to no-shut it without the "none" fallback?
>
> Why not - since You already have been authenticated.
>
> >
> > What if the AAA server is unreachable and you authenticate
> > with a "none" or
> > "local" fallback.  You would be "authenticated" but if the
> > AAA server is
> > unreachable, will you be able authorized without the "none"
> > fallback?  I
>
> Sure, as soon as condition "to be authenticated" is valid/completed You
will
> get exec, netw services or commands
>
>
> > don't think so, but we can lab it up.
> >
> > HTH,
> >
> > -Bob Sinclair
> >  CCIE #10427, CISSP, MCSE
> >
> > ----- Original Message -----
> > From: "Volkov Dmitry" <dmitry.volkov@xxxxxxxxxx>
> > To: "'Bob Sinclair'" <bsin@xxxxxxx>; <security@xxxxxxxxxxxxxx>
> > Cc: <ccielab@xxxxxxxxxxxxxx>
> > Sent: Monday, November 03, 2003 6:10 PM
> > Subject: RE: aaa authorization (last method)
> >
> >
> > > Bob,
> > >
> > > I read it before but didn't get clarity...
> > > It appears to me both last resort  methods "none" and
> > "if-authenticated"
> > are
> > > the same when they used as last one in authorization process.
> > >
> > > I don't get the difference.
> > > Can You be not authenticated and still proceed authorization ?
> > >
> > >
> > > Thanks,
> > > Dmitry
> > >
> > > > -----Original Message-----
> > > > From: Bob Sinclair [mailto:bsin@xxxxxxx]
> > > > Sent: Monday, November 03, 2003 5:54 PM
> > > > To: Volkov Dmitry; security@xxxxxxxxxxxxxx
> > > > Cc: ccielab@xxxxxxxxxxxxxx
> > > > Subject: Re: aaa authorization (last method)
> > > >
> > > >
> > > > Dmitry,
> > > >
> > > > Most of the docs do indicate that "if-authenticated" should
> > > > normally be the
> > > > last method: either you are authenticated and therefore
> > > > permitted, or you
> > > > are not authenticated and the method fails - failing a method
> > > > does not allow
> > > > you to try other methods.   Adding the "none" option
> > appears to be a
> > > > fail-safe in the case of a down or unreachable server.  See
> > > > the link below:
> > > >
> > > > http://www.cisco.com/en/US/partner/netsol/ns341/ns396/ns7/ns18
> > > > /networking_solutions_design_guide_chapter09186a00800f48eb.htm
> > > > l#1009459
> > > >
> > > >
> > > > -Bob Sinclair
> > > >  CCIE #10427, CISSP, MCSE
> > > >
> > > > ----- Original Message -----
> > > > From: "Volkov Dmitry" <dmitry.volkov@xxxxxxxxxx>
> > > > To: <security@xxxxxxxxxxxxxx>
> > > > Cc: <ccielab@xxxxxxxxxxxxxx>
> > > > Sent: Monday, November 03, 2003 10:36 AM
> > > > Subject: aaa authorization (last method)
> > > >
> > > >
> > > > > Does it make any sense to use both methods:
> > > > "if-authenticated" and "none"
> > > > > within the same aaa authorization list.
> > > > > for ex : aaa authorization exec TEST group tacacs+
> > > > if-authenticated none
> > > > >
> > > > > from com ref:
> > > > > If-AuthenticatedThe user is allowed to access the
> > > > requested function
> > > > > provided the user has been authenticated successfully.
> > > > > NoneThe network access server does not request
> > > > authorization information;
> > > > > authorization is not performed over this line/interface.
> > > > >
> > > > > Is it possible: to be not authenticated (for any
> > reasons) and still
> > > > request
> > > > > authorization ?
> > > > > AFAIK authorization happens after authentication (logically).
> > > > > What is the difference to use "if-authenticated" comparing
> > > > with "none" in
> > > > > this context ?
> > > > >
> > > > > Thanks,
> > > > > Dmitry