On Apr 15, 2007, at 5:42 AM, D'Arcy J.M. Cain wrote:

> On Sun, 15 Apr 2007 01:24:49 -0700
> Bryan Phillippe <bryanp35@comcast.net> wrote:
>> I would like to conduct some ethernet network testing using a NetBSD
>> client & server configuration.  The unusual part about this is that I
>> want my configuration to be a single NetBSD system functioning as
>> both a client and a server, physically sending network traffic out on
>> interface and back into another, using a cross-cable.
>
> I'm not sure exactly what you are trying to test here but if you get
> too convoluted you may change the tested system too much.  Is it
> impossible to find one more machine on the network that can run NAT?

I'm trying to test an ethernet switch.  I have a single workstation that
already has multiple NICs in it, and I'd like to be able to use it  
for this
purpose.  In addition to saving space & power, it will also be easier if
I only have to manage a single system.  Furthermore, I could run
simultaneous captures (e.g. tcpdump) on both interfaces, which
also simplifies timestamp comparison.

If I can't find a simple way (I'll try Manuel's suggestion of manually
munging routes first), I'll probably just use one of these:

http://www.ssi.bg/~ja/#loop
http://norvegh.com/ntools/index.php