RE: NTP authentication

From: Sharma, Shyam (shyam.sharma@hp.com)
Date: Fri May 05 2006 - 13:38:45 ART


Hi All,

Could any one send me my Active Key initial PIN?

I can't use my card without that.

Thanks,

Shyam
713-269-6204

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Luis Rueda
Sent: Monday, May 01, 2006 2:59 PM
To: Schulz, Dave; Petr Lapukhov
Cc: Michael; ccielab
Subject: RE: NTP authentication

Dave,

I took a look at the RFC and surprisingly, the key is mentioned, but it
was not clear to me if they have to match. Take a look at Appendix C.

http://www.faqs.org/rfcs/rfc1305.html

Regards,

Luis

________________________________

De: Schulz, Dave [mailto:DSchulz@dpsciences.com] Enviado el: Monday, May
01, 2006 9:07 AM
Para: Petr Lapukhov
CC: Luis Rueda; Michael; ccielab
Asunto: RE: NTP authentication

Nice explanation, Petr. So, then you are saying the keys must
agree...not only in the key itself, but also the number.

Dave Schulz,

Email: dschulz@dpsciences.com <mailto:dschulz@dpsciences.com%20>

________________________________

From: Petr Lapukhov [mailto:petrsoft@gmail.com]
Sent: Monday, May 01, 2006 9:58 AM
To: Schulz, Dave
Cc: Luis Rueda; Michael; ccielab
Subject: Re: NTP authentication

Guys,

I think I got some logic behind this..

Okay, so what does that mean :))

First of all, all authenticated packets carry key numbers with them.
Next:

1) We have "active" and "passive" modes. Active mode (peer active,
client)
deduces key from "key" parameter in command line (ntp peer key, ntp
server key).

Passive mode deduces key number from incoming "active" packet, and look
up key-string in it's keyring. E.g when server receives a query with
key, it replies with the key-string under same key-number from it's
key-ring.

2) As i get it, ony "synchronization" packets needs to be authenticated.

That is, only packets that can change our clock needs to be
authenticated.

So, "ntp server" is not required to check authentication in query
packet.
It does something else, though. More on that later.

3) Authentication is not enabled until we enter "ntp authenticate"
command.
When "ntp authenticate'" is turend on, we inspect every "sync" packet to
get key number. We then look that key-string by it's number in our key
ring, verify md5 checksum, and if the key is trusted, we consider packet
to be

authenticated.

4) As i said, when a "passive" router receives packet from "active"
neighbor,
it looks up it key ring. Next, if this is "sync" packet, we need to
validate it.
That is, key needs to be trusted, and md5 sum must match.

If this is a "query" packet, we simple reply with "sync" packet, and
include key from our key-ring in reply, looking that key by key-number
from packet.

That's all i get :) By the way, I discovered that we dont need to enable
"ntp authentication" on server either. It still does respond with
appropriate keys.

HTH
Petr

2006/5/1, Schulz, Dave <DSchulz@dpsciences.com>:

That is what I was thinking, but after doing the debugs....I didn't see
this. I'll run it again.

Dave Schulz,

Email: dschulz@dpsciences.com <mailto:dschulz@dpsciences.com%20>

________________________________

From: Petr Lapukhov [mailto:petrsoft@gmail.com]
Sent: Monday, May 01, 2006 9:05 AM
To: Schulz, Dave
Cc: Luis Rueda; Michael; ccielab
Subject: Re: NTP authentication

Actually, if you do a "debug ntp authentication" you will see, that NTP
packets carry key number with them :))

I try to dig that topic, since information on NTP is scarse and vague
:))

Petr

2006/5/1, Schulz, Dave <DSchulz@dpsciences.com >:

Luis -

Do you have a configuration where this worked successfully? I labbed it
up and could only get the authentication to work if the key #'s are the
same.

Dave Schulz,
Email: dschulz@dpsciences.com

-----Original Message-----
From: nobody@groupstudy.com [mailto: nobody@groupstudy.com
<mailto:nobody@groupstudy.com> ] On Behalf Of Luis Rueda
Sent: Sunday, April 30, 2006 4:09 PM
To: Michael; ccielab
Subject: RE: NTP authentication

If you mean like OSPF that you have to use the same number on both ? I'm
pretty sure not. I have used them with different numbers and they all
work.

Diferent numbers are supported because maybe you have different servers
with different passwords....

Hope it helps.

Luis

-----Mensaje original-----
De: nobody@groupstudy.com [mailto: nobody@groupstudy.com
<mailto:nobody@groupstudy.com> ] En nombre de Michael Enviado el:
Sunday, April 30, 2006 3:05 PM
Para: ccielab
Asunto: RE: NTP authentication

Hi Groupstudy,

Is there anyone that can please comment / help on this subject?

Thanks in advance,

Michael

  _____

From: Michael [mailto: mamiller2@comcast.net
<mailto:mamiller2@comcast.net> ]
Sent: Sunday, April 30, 2006 2:43 AM
To: ccielab (ccielab@groupstudy.com)
Subject: NTP authentication

Hey all~

Can anyone confirm that ntp key id numbers also need to be the same for
peers using md5 authentication? I have been experimenting with
different configurations and this all that seems to work.

P1R1-2511#show run | inc ntp

ntp authentication-key 1 md5 0941571D100812 7

ntp authentication-key 3 md5 00070155 7

ntp authenticate

ntp trusted-key 1

ntp trusted-key 3

ntp trusted-key 6

ntp clock-period 17180181

ntp peer 10.10.3.3 key 3

ntp peer 10.10.4.4 key 1

ntp peer 10.10.5.5 key 1

ntp peer 10.10.6.6 key 1

ntp peer 10.10.7.7 key 1

ntp peer 10.10.8.8 key 1

ntp peer 10.10.9.9 key 1

ntp server 66.90.78.182

P1R1-2511#

CR3#show run | inc ntp

ntp authentication-key 3 md5 104D1B4A 7

ntp authenticate

ntp trusted-key 3

ntp clock-period 17208479

ntp source Loopback0

ntp peer 10.10.1.1 key 3 prefer

CR3#



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