Some help with broadcasts through a Linux system

Jasper van der Neut jasper.vanderneut at
Wed Feb 3 09:00:54 GMT 1999

Richard Sharpe wrote:
> Hi,
> I am having problems getting broadcasts through a Linux system.
> Here is the config:
>      ----------------[Linux Box]------------------
> I have it set up with ip_forward=1.
> However, when I ping from, responds,
> and I see nothing on the subnet.
> The linux box is running a 2.0.36 kernel.
> It seems that Linux feels that it should not have to forward the broadcast
> datagrams.

Which is the correct behaviour.

> Does anyone have any clues?

If you want to forward your netbios datagram broadcasts you have to do
more than just forwarding because the data contains ip-addresses too.

I've solved this problem by writing a patch for Samba which 'glues' 
the subnets of my linux firewall together. You can find the code
at . The code is not
up-to-date with the latest Samba because I'm abroad, but that's an
exercise for the reader ;)


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