Configuring FreeBSD gateway/firewall?

John C johnc909 at
Sun Apr 13 22:27:47 PDT 2003

Ahh ... And I thought my first query was a bit too specific ...
Here's my original message:

I am attempting to turn a PC into a gateway/firewall for my home network.
My ISP is Comcast ... So whatever ramifications therein, for better or
worse, apply to my predicament ...

I've gotten both interfaces up and working, but I can't seem to get it to
switch packets from within the subnet out into the internet.  The kernel is
pretty much GENERIC 4.7, except with the GATEWAY option set, plus with

In sysctl.conf

My configuration is as follows:

Gateway machine: "argonath"
External network interface: sis0 (netgear card, ip provided by
Default route: (presumably my cable modem)
Private subnet interface: rl0

Secondary subnetted machine "shelob":
Default route:

I can ping & ssh to "argonath" from "shelob", and can reach the internet
from argonath's rl0 ... But like I said, the gateway action isn't happening.

One other thing I found odd is that when my secondary machine is plugged
directly into the Comcast subnet, it reports a default route of,
which seems more right, but I don't have experience enough in these matters
to say, and what documentation I've found isn't specific enough to give me a
clue about how to solve this problem ...

Please help?


On 4/13/03 9:54 PM, "Andrew Brampton" <andrew at> wrote:

> I believe there is something wrong with your configuration...
> Ask a vague question, and get a vague answer, ask a specific question, and
> we will give you a specific answer. Please provide as much details as you
> can when asking your question, and exactly what the problem is.
> Andrew
> ----- Original Message -----
> From: "John C" <johnc909 at>
> To: <freebsd-questions at FreeBSD.ORG>
> Sent: Monday, April 14, 2003 5:24 AM
> Subject: Configuring FreeBSD gateway/firewall?
>> Hello ... I'm trying to configure a FreeBSD machine to act as a gateway
>> between my ISP network (Comcast) and my own private subnet.
>> I've followed all documentation so far for this type of configuration ...
>> Pleasse help?
>> -john
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