Subject: Re: bpf write() to local host
To: Andrew Brown <>
From: Manuel Bouyer <>
List: tech-net
Date: 01/19/2003 16:53:19
On Sat, Jan 18, 2003 at 05:36:35PM -0500, Andrew Brown wrote:
> >I'd like to commit the attached patch. This patch makes packets coming 
> >to ether_output with the pseudo-family pseudo_AF_HDRCMPLT and a dest address
> >matching the local host redirected or copied to ether_input() (depending
> >if they are unicast or not). Only bpf write() seems to use pseudo_AF_HDRCMPLT
> >right now.
> >This is to solve a problem with simh: it uses bpf writes to send packets,
> >which makes it impossible to send packets to the local machine.
> >With this change (and a fix to simh) I can NFS mount from a NetBSD/vax in simh
> >a partition of the NetBSD/i386 hosting it.
> i haven't skimmed the patch, but i believe the "standard" solution to
> this problem is to tell simh to use a second ethernet adapter in the
> host machine.  i can certainly ping (or mount nfs volumes from) my
> laptop from the simulator running on my laptop if i have two nics in
> it.

Hum, reading the sources I can't see how adding a second NIC would help.
Maybe it's hardware-dependant ? Does ifconfig have the SIMPLEX flag
for the ethernet you use with simh ?

Manuel Bouyer <>
     NetBSD: 23 ans d'experience feront toujours la difference