How to get my Dad's Win2k system to access internet through my FreeBSD 6.2 system

Michael Powell nightrecon at
Tue Oct 14 03:42:26 PDT 2008

Jeremy Chadwick wrote:

> On Tue, Oct 14, 2008 at 04:55:11AM -0400, Michael Powell wrote:
>> Next, you will want to configure your FreeBSD machine as a NAT gateway.
>> In your /etc/rc.conf you will want something like gateway_enable="YES"
>> and some form of firewall initialization[1]. The gateway_enable is what
>> allows the forwarding of packets between your rl0 and your rl1, but the
>> activation of NAT functionality is usually a function contained within a
>> firewall. So conceptually, the firewall will be "in between" rl0 and rl1.
>> There are three different firewalls you can choose from. Configuring the
>> firewall is usually where the inexperienced get stuck. This subject
>> material is beyond the scope of this missive, and you would do well to
>> start reading in the Handbook. But essentially, when you configure NAT in
>> the firewall your rl0 (connected to the ISP) will be assigned a "Public"
>> IP address and the NAT function will translate between "Public" and
>> "Private".

With respect to "NAT", the caveat here is the assumption that your DSL/Cable
modem is *not* already performing NAT. The situation you do not want to get
into is having *two* NATs. The content herein is assuming that the external
(rl0) interface is getting assigned a "Public" IP from the ISP. 
> Doesn't he need to also set sysctl net.inet.ip.forwarding=1 for his
> box to act as a gateway?  Or is this handled by the NAT portion?
The gateway_enable="YES" in /etc/rc.conf sets this.


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