From: Rob Webber (rwebber@xxxxxxxxxxxx)
Date: Tue May 08 2001 - 16:30:12 GMT-3
Actually I don't think I agree that the password needs to be the same on
both routers. Usually it is - certainly for simplicity you would want it
that way (but when is the CCIE lab ever simple?)
My understanding is that two-way CHAP authentication is basically two
separate CHAP authentications happening at the same time. Thus the passwords
do not have to be the same for both directions. That is also why you don't
have to run CHAP in both directions - you can just have one-way
authentication if you want it. I dug this up from my log of my old configs -
it uses CHAP with different usernames and passwords on each end. I have
since sold my routers, but Grant - perhaps you could try this config and let
us know what you find out.
Thanks - Rob.
my configs:
hostname r5
!
!
username abc password 0 what
username xyz password 0 mypassword
!
interface BRI0
encapsulation ppp
ppp authentication chap
ppp chap hostname abc
!
hostname r7
!
!
username abc password 0 mypassword
username xyz password 0 what
!
interface BRI0
encapsulation ppp
ppp authentication chap
ppp chap hostname xyz
!
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Grant Patten
Sent: Tuesday, May 08, 2001 2:53 PM
To: 'Christopher M. Heffner '; Grant Patten; 'Khalid Nafie '; 'BootCamp
'
Subject: RE: CHAP Authentication
Thanks alot to everybody who helped me out on this one. It makes sense now.
Thanks,
Grant
-----Original Message-----
From: Christopher M. Heffner
To: Grant W. Patten; Khalid Nafie; BootCamp
Sent: 5/8/01 1:42 PM
Subject: RE: CHAP Authentication
Grant:
The username password is required on both sides to prove that
they both know the same password.
When the first router sends a challenge to a remote router then the
remote router will look up the username password based on the hostname
sent by the first router. The remote router will then run the MD5 hash
against the challenge using the password from the username command.
At the same time, the first router that sent the challenge will
be looking up the username password of the remote router and running the
same challenge through the MD5 hash using the remote router's password
hence they have to be the same password. When the first router computes
the answer to the challenge, it will then compare the response from the
remote router that comes back. Both answers must be the same hence both
sides know the proper password and neither side ever sends the password
across the link.
And then the whole thing starts the other way since
router-to-router is by default two-way auth.
This is covered in the Building Cisco Remote Access Networks (BCRAN)
course.
HTH,
Christopher M. Heffner
Certified Cisco Systems Instructor
CCSI, CCNA, CCDA, CCIE Candidate
MCT, MCSE, MCNI, MCNE, CLI, CLP, ASE, CTT, A+
cheffner@certified-labs.net
-----Original Message-----
From: Grant W. Patten [mailto:gpatten@lucent.com]
Sent: Tuesday, May 08, 2001 2:59 PM
To: Khalid Nafie; BootCamp
Subject: RE: CHAP Authentication
That works just fine. Then is it fair to say definitively that CHAP
only
works when both sides are using the same password and it isn't possible
to
configure it with different passwords? If so, then why does the
configuration require username/password to be configured for each remote
peer?
Thanks,
Grant
At 08:41 PM 5/8/2001 +0300, Khalid Nafie wrote:
>Hi Grant,
> Try to use the same password for both usernames.
>================================================
>Yours,
>Khaled Nafie
>Network Engineer
>Customer Services
>MCSE,CCDP,CCNP VOCIE ACCESS
>NCR Corporation, Kuwait
>Mob.: +965-9872046
>Tel : +965- 2412201, 2412203
>Fax : +965-2413075
>
> > ----------
> > From: Grant Patten[SMTP:gpatten@lucent.com]
> > Reply To: Grant Patten
> > Sent: Tuesday, May 08, 2001 8:12 PM
> > To: 'ccielab@groupstudy.com'
> > Subject: CHAP Authentication
> >
> > I'm struggling to get a good understanding of how exactly CHAP
> > Authentication works. I think I'm missing something fundamental and
> > hopefully one of you can help me out. Thanks.
> >
> > When I use the configuration below, I get the following debug
messages:
> >
> > 1d15h: BR0:1 PPP: Treating connection as a callout
> > 1d15h: BR0:1 PPP: Phase is AUTHENTICATING, by both
> > 1d15h: BR0:1 CHAP: Using alternate hostname ISDN2
> > 1d15h: BR0:1 CHAP: O CHALLENGE id 14 len 26 from "ISDN2"
> > 1d15h: BR0:1 CHAP: I CHALLENGE id 14 len 26 from "ISDN1"
> > 1d15h: BR0:1 CHAP: Using alternate hostname ISDN2
> > .d15h: BR0:1 CHAP: O RESPONSE id 14 len 26 from "ISDN2"
> > 1d15h: BR0:1 CHAP: I FAILURE id 14 len 25 msg is "MD/DES compare
failed"
> >
> >
> > Here is the relevant portions of the configs I'm using on R1 and R2.
I
> > changed the encrypted ppp chap password to what I actually set:
> >
> >
> > R2
> >
> > hostname R2
> > !
> > !
> > username ISDN1 password 0 CCIE
> > !
> > !
> > interface BRI0
> > ip address 147.10.1.2 255.255.255.0
> > no ip directed-broadcast
> > encapsulation ppp
> > dialer map ip 147.10.1.1 name ISDN1 broadcast 8358661
> > dialer-group 1
> > isdn switch-type basic-ni
> > isdn spid1 0835866201
> > isdn spid2 0835866401
> > ppp authentication chap
> > ppp chap hostname ISDN2
> > ppp chap password cisco
> >
> > R1
> > hostname R1
> > !
> > !
> > username ISDN2 password 0 cisco
> > !
> > interface BRI0
> > ip address 147.10.1.1 255.255.255.0
> > no ip directed-broadcast
> > encapsulation ppp
> > dialer map ip 147.10.1.2 name ISDN2 broadcast
> > dialer-group 1
> > isdn switch-type basic-ni
> > isdn spid1 0835866101
> > isdn spid2 0835866301
> > ppp authentication chap
> > ppp chap hostname ISDN1
> > ppp chap password CCIE
> > **Please read:http://www.groupstudy.com/list/posting.html
**Please read:http://www.groupstudy.com/list/posting.html
**Please read:http://www.groupstudy.com/list/posting.html
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