Bill,
 
Firstly I appreciate you patient and time to give me detail reply.  Unfortunately, I am still unable to get it thru.  Firstly, under the Topology page, there are only 3 columns: start from the left - Name, IP Address, Network mask.  There is no IP Addresses behind interface column.  After I select the interface and click Edit button, the Interface Properties comes out but there is no "Topology" tab.  Therefore, I cannot set External, Internet or IP range.  Could it be due to different version of CheckPoint (I am using CP FP2 NG) or did I look at different area?
 
Thanks,
 
Ray
 
----- Original Message -----
From: Bill
Sent: Wednesday, 25 September, 2002 01:28 p
Subject: Re: [FW-1] Fw: [FW-1] Anti-spoofing warning

I will answer the questions inline -- see below.
Thanks for your advice.  I believe network object means the CheckPoint Host (Firewall) and opened it to Topology tab in Policy Editor.  There were two interfaces: eth-s1p1co and eth-s2p1co inside the table. 
 
[Bill]  In the "topology" sectin there is a summary section which lists the interfaces.  In the columns to the right, you will see what anti-spoofing option (if any) is already selected for each interface.
 
The first one is connected to internet using a public IP and the second one to the local LAN using a private IP for the firewall.  After I clicked "Get Topology .." button, a caution showed that "Topology and anti-spoofing settings that are already defined will be overwritten by results of this operation that contradict them, if any.  Do you want to continue?"  It seems the anti-spoofing has been set before.  I have a query about the IPs to be filled in before I continue and seek your further advice.
 
[Bill]  First of all, that message is a default.  You will always see it "just in case."  Anyway, you can view or edit settings by selecting the interface (i believe you can double-click or hit the "edit" button after selecting).  This will allow you to select an interface and view the current configuration.  From here you can change the options without "getting" your interfaces again.  You will only need to "get" the interfaces again if they are not correct.  Use your Nokia Voyager to verify that the interfaces are correct.
 
1.  For the interface to internet, what should I put in the IP column?
 
[Bill]  You should choose the "external interface" option in general. This is what most people would do.  If the firewall is only used for limited purposes AND external ip addresses, you could limit this further by creating a network object which contains the necessary ip addresses and select that.
 
2.  For local LAN interface, our workstations are in the range of 192.168.0.11 to 192.168.0.40.  How can I put a range of IP as there is only one space available?  Other IPs, i.e., network printer IPs, are not needed to be included here since they do not need to pass thru the firewall.
 
[Bill]  There are various ways to deal with interfaces in general.  You can choose the option which allows for all ip addresses contained within the configuration of the interface.  If for example your interface was configured as 192.168.0.1/24 it would allow any 192.168.0.1 through 192.168.0.255 addresses through.  You can also choose the option which allws for selecting a "single" network object.  I am not sure about the total list of what type of objects can be used here maybe somebody else can help you there.  One option though, is to create a group with all the individual workstations (in your case 11 through 40) and select that group.  This does not scale well, but it is an option.  Another option might be able to create an "ip address range" object and use that here.  I am not sure if this option is allowed.  The "ip address range object" had very specific uses in the past.  Another option would be to create a network object or objects which is/are a subset of the actual network which would account for the necessary ip addresses.  This can also be tedious and is probably not necessary.  In your case, I would probably recommend using the network interface option and using the policy rulebase to further limit that to necessary objects.  No point in making your life more difficult than necessary for minimal gains  ;~}.  Use your common sense here.  Use the principle of least privilege where possible.
 
Thanks,
 
Ray
 
 
From: Bill

Sent: Wednesday, 25 September, 2002 03:27 a

Open up the network object in the policy manager. Click on the topology tab. "Get" all your interfaces and verify that they are correct. Then drill down into each interface and choose from the options. I believe they are (not necessarily in the same order or words):

--network defined by your interface configuration

--a network object or group which would define all allowable networks

--external interface

The anti-spoofing is used to tell the firewall what source ip addresses are valide for traffic INBOUND on the port/interface in question. Be very careful and make sure that you are accounting for all necessary networks. I would recommend that you log this information as well so you can "see" when something is not being allowed through and determine the cause -- right or otherwise.

----- Original Message -----

From: Ray Li

To: [EMAIL PROTECTED]

Sent: Tuesday, September 24, 2002 12:38 PM

Subject: [FW-1] Anti-spoofing warning

I notice that my Nokia firewall shows a warning that "The 2 interface is not protected by the anti-spoofing feature. Your network may be at risk. In the future, it is recommended that you define anti-spoofing protection before installing the Security Policy." during bootup. I am using CheckPoint VPN Pro NG. To fix this problem, can someone help me configure the anti-spoofing on the CheckPoint NG version.

Thanks,

Ray

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