Re: Windows 2k arp table problem

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From: André (A.Pirard_at_ulg.ac.be.look.what.they.ve.done.to.e-mail.ma)
Date: 02/13/05 

Date: Mon, 14 Feb 2005 00:05:01 +0100

You people over there are amazingly hard to understand.
I gave that guy with an invalid e-mail address a full, knowledgeable
solution to his problem in his own language and there is no single
word in return.

On Wed, 02 Feb 2005 03:08:04 +0100, André
<A.Pirard@ulg.ac.be.look.what.they.ve.done.to.e-mail.ma> wrote:

>Hi,
>
>When a Cisco router (thinks it) has the best route to some
>destination, in can proxy-arp for that destination, that is, reply
>with its MAC address to any arp for any address to that destination.
>192.168.2.254 has the best route for 1.1.1.1, hence its reply and the
>ARP entry in the PC.
>"best route" = a route not going back through network 192.168.2.0.
>
>So either you disable proxy-arp with the following command on Cisco
>no ip proxy-arp
>if that suites you, or you get the routes right in both routers.
>As all routers on a lan must normally have the same view of the
>routes, the thing to do is to run a routing protocol such as OSPF or
>RIP (best is V2) to tell their routes one to the other.
>And then, a 192.168.2.x host sending a packet to the wrong router will
>receive an ICMP redirect that will change its mind towards the other.
>Hosts on 192.168.2.0 can run the RIP listener service to get the
>correct routing table, and their destination outright.
>Of course, only one router must have a default route or any other
>route, at least, you must manage for only one router to announce each.
>
>Hoping it will help (sure it will if you understood).
>Just passing by this group, any thanks are best e-mailed.
>
>André.
>
>
>On Tue, 1 Feb 2005 01:11:03 -0800, "slickric"
><slickric@discussions.microsoft.com> wrote:
>
>>In my LAN there are 2 gateway. One is for DSL 192.168.2.253 with a firewall
>>attached and one is for leased line conneted to another site 192.168.2.254.
>>My problem is most of my user's PC will use DHCP and have 192.168.2.253 as
>>the gateway since we are not allow every user has the internet access rights.
>>So i can set the internet access rights restriction through the firewall.
>>But recently I found out that some of my user manully input 1.1.1.1 as the
>>default gateway and their PC also gets into the internet from 192.168.2.254
>>which is conneted to other site. And the fake default gateway will obtained
>>the same MAC address from the Cisco which is 192.168.2.254. I tried in W2k
>>and XP both have the same result. I have tried to solve it for more than 2
>>weeks now.. and still don't have any hint at all..... Can anyone help...???
>>
>>Thx in advance!!
>>
>>C:\Documents and Settings\Ricky>ipconfig /all
>>
>>Windows 2000 IP Configuration
>>
>> Host Name . . . . . . . . . . . . : cvr-mis-06
>> Primary DNS Suffix . . . . . . . :
>> Node Type . . . . . . . . . . . . : Hybrid
>> IP Routing Enabled. . . . . . . . : No
>> WINS Proxy Enabled. . . . . . . . : No
>>
>>Ethernet adapter 3:
>>
>> Connection-specific DNS Suffix . :
>> Description . . . . . . . . . . . : Realtek RTL8139(A) PCI Fast
>>Ethernet
>>
>> Physical Address. . . . . . . . . : 00-0A-EB-2C-FB-CF
>> DHCP Enabled. . . . . . . . . . . : No
>> IP Address. . . . . . . . . . . . : 192.168.2.242
>> Subnet Mask . . . . . . . . . . . : 255.255.255.0
>> Default Gateway . . . . . . . . . : 1.1.1.1
>> DNS Servers . . . . . . . . . . . : 192.168.2.4
>>
>>C:\Documents and Settings\Ricky>route print
>>=====================================================
>>0x1 ........................... MS TCP Loopback interface
>>0x1000003 ...00 0a eb 2c fb cf ...... NDIS 5.0 driver
>>
>>=====================================================
>>
>>Active Routes:
>>Network Destination Netmask Gateway Interface Metric
>> 0.0.0.0 0.0.0.0 1.1.1.1 192.168.2.242 1
>> 127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
>> 192.168.2.0 255.255.255.0 192.168.2.242 192.168.2.242 1
>> 192.168.2.242 255.255.255.255 127.0.0.1 127.0.0.1 1
>> 192.168.2.255 255.255.255.255 192.168.2.242 192.168.2.242 1
>> 224.0.0.0 224.0.0.0 192.168.2.242 192.168.2.242 1
>> 255.255.255.255 255.255.255.255 192.168.2.242 192.168.2.242 1
>>Default Gateway: 1.1.1.1
>>=====================================================
>>Persistent Routes:
>> None
>>
>>C:\Documents and Settings\Ricky>arp -a
>>
>>Interface: 192.168.2.242 on Interface 0x1000003
>> Internet Address Physical Address Type
>> 1.1.1.1 00-0d-65-ab-61-47 dynamic
>> 192.168.2.254 00-0d-65-ab-61-47 dynamic
>>
>>C:\Documents and Settings\Ricky>tracert www.yahoo.com
>>
>>Tracing route to www.yahoo.akadns.net [216.109.117.205]
>>over a maximum of 30 hops:
>>
>> 1 15 ms <10 ms <10 ms 192.168.2.254
>> 2 <10 ms 15 ms 16 ms 10.114.28.45
>> 3 15 ms 32 ms 31 ms 10.114.1.218

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