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 From:  Jim Thompson <jim at netgate dot com>
 To:  Chris Buechler <cbuechler at gmail dot com>
 Cc:  Paul Vaughan <pvaughan at san dot rr dot com>, m0n0wall at lists dot m0n0 dot ch
 Subject:  Re: [m0n0wall] Two IP address for WAN
 Date:  Wed, 23 Mar 2005 20:06:59 -1000
On Mar 23, 2005, at 1:13 PM, Chris Buechler wrote:

> On Wed, 23 Mar 2005 14:55:09 -0800, Paul Vaughan <pvaughan at san dot rr dot com> 
> wrote:
>> Two IP address for WAN
>>
>> My Internet ISP is my cable company.  So, i connect through a cable
>> modem.  I setup a m0n0wall firewall behind the cable modem.  I gets 
>> it's
>> IP address via DHCP.  When I go to the webGUI Configuration page under
>> Status|Interfaces it lists the WAN interface as indicated below:
>>
>> Status                up
>> MAC address   00:xx:xx:xx:xx:xx
>> IP address         XX.YY.ZZZ.153
>> Subnet mask      255.255.248.0
>> Gateway            XX.YY.ZZZ.1
>>
>> Why the two addresses?  Gateway and IP.
>>
>
> The IP is your public IP, the gateway is its default gateway, i.e. the
> ISP's router.
>
>
>> I can ping the gateway from outside the LAN but can't ping the IP
>> address.  What gives?
>
> m0n0wall blocks ICMP by default so your WAN IP won't respond to pings.
>  Typically ISP's won't drop it on their routers.

Your netmask (255.255.248.0) is a /21, which is a combination of 8 of 
the old "class C" networks.

Does your cableco really run a 2048 node LAN on the backside of your 
cable modem?