[isapros] Re: ISA DHCP

  • From: "Amy Babinchak" <amy@xxxxxxxxxxxxxxxxxxxxxxxxxx>
  • To: <isapros@xxxxxxxxxxxxx>
  • Date: Wed, 1 Nov 2006 09:25:53 -0500

So I created a new SBS box last weekend and have not installed ISA Sp2
yet. Checked the DHCP rules and they are same as after ISA SP2. So it
appears that these are the default SBS DHCP rules. I still don't
understand why they are working. Guess I have a mental block on it.
Anyone care to educate me?

 

Here's what we have:

 

System Policy

            DHCP (Request) From Localhost to Anywhere for All Users

            DHCP (Reply) From Internal to LocalHost for All Users

 

Firewall Policy

            DHCP (Reply) From External to LocalHost for All Users

 

 

Amy Babinchak

 

 

 

________________________________

From: isapros-bounce@xxxxxxxxxxxxx [mailto:isapros-bounce@xxxxxxxxxxxxx]
On Behalf Of Jim Harrison
Sent: Friday, October 27, 2006 12:17 AM
To: isapros@xxxxxxxxxxxxx
Subject: [isapros] Re: ISA DHCP

 

We need to clarify *which* DHCP rules you're talking about...

1.      Default System DHCP policies allow

a.       DHCP Request from Local Host to Internal (UDP:68 --> UDP:67)

b.      DHCP Reply from Internal to local host (UDP:67 --> UDP:68)

2.      SBS DHCP policies allow

a.       DHCP Request from Internal to Local Host (UDP:68 --> UDP:67)

b.      DHCP Reply from Local Host to Internal (UDP:67 --> UDP:68)

 

If a DHCP relay is in the path between the DHCP client and server, the
traffic between the server and the relay will actually appear as UDP:67
--> UDP:67 regardless of direction.  Note that ISA doesn't make any
distinction between this and DHCP Request traffic, since both are
destined for UDP:67.  Is there a DHCP helper in either of these
environments?

 

Based on the log excerpt you provided, it appears that it's the array
rules that are failing.

Is that correct?

 

From: isapros-bounce@xxxxxxxxxxxxx [mailto:isapros-bounce@xxxxxxxxxxxxx]
On Behalf Of Amy Babinchak
Sent: Thursday, October 26, 2006 7:11 PM
To: isapros@xxxxxxxxxxxxx
Subject: [isapros] Re: ISA DHCP

 

In SBS DHCP rules are automagically created in the system policy.

 

Amy Babinchak

 

Harbor Computer Services

(248) 546-6056 office

(248) 890-1794 mobile

 

http://isainsbs.blogspot.com

http://keepitsecure.blogspot.com

http://www.harborcomputerservices.net

 

     

 

 

________________________________

From: isapros-bounce@xxxxxxxxxxxxx [mailto:isapros-bounce@xxxxxxxxxxxxx]
On Behalf Of Jim Harrison
Sent: Thursday, October 26, 2006 9:26 PM
To: isapros@xxxxxxxxxxxxx
Subject: [isapros] Re: ISA DHCP

 

He doth speaketh truly, doth he.

SBS always had to create an array-level rule allowing DHCP requests &
replies for the internal network.

I 'd be very surprised to see SP2 installation removing those, since the
SBS team had to have tested SP2 as well.

 

From: isapros-bounce@xxxxxxxxxxxxx [mailto:isapros-bounce@xxxxxxxxxxxxx]
On Behalf Of Thomas W Shinder
Sent: Thursday, October 26, 2006 5:20 PM
To: isapros@xxxxxxxxxxxxx
Subject: [isapros] Re: ISA DHCP

 

Hi Amy,

 

I'm not sure what the sceanrio is is. Is there a DHCP server on the ISA
Firewall? If so, there never were any System Policy Rules that allow for
this, you've always had to create your own rules.

 

Tom

 

Thomas W Shinder, M.D.
Site: www.isaserver.org <http://www.isaserver.org/> 
Blog: http://blogs.isaserver.org/shinder/
Book: http://tinyurl.com/3xqb7
MVP -- Microsoft Firewalls (ISA)

 

         

        
________________________________


        From: isapros-bounce@xxxxxxxxxxxxx
[mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Amy Babinchak
        Sent: Thursday, October 26, 2006 3:45 PM
        To: isapros@xxxxxxxxxxxxx
        Subject: [isapros] ISA DHCP

        Here's the promised update for the DHCP stops working issue
after ISA SP2 install. More are starting to show up on the SBS yahoo
group. The server that I've seen belongs to Eriq Neale. I know Tom
Shinder knows him, he's a pretty competent guy from there in Texas. 

         

        Original Client IP      Client Username   Client Agent
Authenticated Client    Service      Server Name Referring Server
Destination Host Name   Transport   HTTP Method URL      MIME Type
Object Source     Source Proxy      Destination Proxy Bidirectional
Client Host Name  Rule  Filter Information      Network Interface Raw IP
Header     Raw Payload     Log Time    Source Port Processing Time
Bytes Sent  Bytes Received    HTTP Status Code Cache Information Log
Record Type   Destination IP    Destination Port  Protocol      Action
Client IP   Source Network    Destination Network     Result Code Error
Information

        0.0.0.0                             CC-SBS      -           UDP
-     -     -                                         -
10/26/2006 8:43:25 AM   68    0     0      0           0x0   Firewall
255.255.255.255   67    DHCP (request)    Denied Connection  0.0.0.0
Internal    Local Host  0xc004000d FWX_E_POLICY_RULES_DENIED      0x0

         

         

        I also ran an ISA info. Checked the server against mine and the
system policy rules for DHCP are identical. Checked the NIC
configurations those look good too. Checked that .255 is part of the
internal network. Checked binding order and where DHCP is bound.
Everything checks out.

         

        If you recreate the DHCP system policy rules as firewall rules,
DHCP works. Saw it with my own eyes. DHCP was working prior to ISA SP2
installation. 

         

        I'm stumped. Anyone?

         

        p.s. I wish you guys would monitor the ISA MVP list as well. 

         

        Amy Babinchak

         

         

         

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