Re: /etc/network/options

[Federico Montesino Pouzols <p5087@quintero.fie.us.es>]

Hello,

>I am not sure what the flag for ip_forwarding quite means.  I know
>the concept and the echo "1" >/proc....
>I don't remember quite where it echoes to, but that's Debians job,
>right?

The exactly echo is (I am checking in 2.2.12) echo "1"> /proc/sys/net/ipv4/ip_forward.


>Does ip_forward=yes simply set this echo "1" >/proc... to be
>enabled?

The kernel option ip_forward enables the kernel to resend packets
received with a destination address accesible but not local (that is,
enables your host to do routing work). The 'echo "1">...' is the way
to say to the kernel that you really want it to do this. Unless you
put 'echo "1"...' somewhere, the kernel will not start to
resend/forward ip packets although it has the necessary code built
in. They are both necessary but not the same.

You can thing of ip_forward=yes as a "kernel-compile-level" enable and
 of 'echo "1" ...' as a "network-configuration-level" enable.

So, if you are setting up a router or something like that, you should
select ip_forwarding before compiling the kernel, and then put
the "echo ..." somewhere or let debian conf to do so.

It is described somewhere in the kernel menuconfig/xconfig documentation.

Good luck!