Network Numbering Problem, 3-4 nics instead of Hub

[Bob Chiodini]

On Wed, 2005-04-13 at 12:28 -0700, Johnny Smith wrote:
> --- "Ed K." <ed at hp.uab.edu> wrote:
> > On Wed, 13 Apr 2005, Johnny Smith wrote:
> > > Hallow all,
> > >
> > > I have a network numbering/routing question.
> > >
> > > I have a pretty standard home network with a linux
> > > firewall/NAT box feeding a
> > > hub to what is is usually 3-5 machines.
> > >
> > > Can I eliminate the hub and use 3+ nics on the
> > > firewall box and
> > > 'how' would I number them???
> > >
> > > I have set this up once before but I find that
> > > the various hosts connected to the firewall can
> > not
> > > see or access each other, but all can access the
> > net.
> > >
> > > what am I doing wrong below ?
> > >
> > > Internet==> firewall/NAT Machine [with multiple
> > Nics
> > > and CrossOver CAbles to Hosts] ==>
> > >
> > > ==>  eth0  [ 10.0.0.1/255.0.0.0]  ==>
> > > host-1 eth0= 10.0.0.2/ 255.0.0.0
> > >
> > > ==>  eth1  [ 172.16.0.1/255.255.0.0] ==>
> > > host-2 eth0= 172.16.0.2/255.255.0.0
> > >
> > > ==>  eth2  [ 192.168.0.1/255.255.255.0] ==>
> > > host-3 eth0= 192.168.0.2/255.255.255.0
> > >
> > >
> > > The method above did now allow each host to see &
> > > access each other, they could access the internet.
> > >
> > >
> > >
> > > Could the following Alternative Numbering Work ??
> > >
> > > Internet==> firewall/NAT Machine
> > > [with multiple Nics and 'CrossOver Cables'
> > > to 'multiple' Hosts] ==>
> > >
> > > ==>  eth0  [ 172.16.0.1.255.255.0.0]  ==>
> > > host-1 eth0= 172.16.0.2/255.255.0.0
> > >
> > > ==>  eth1  [ 172.17.0.1.255.255.0.0]  ==>
> > > host-2 eth0= 172.17.0.2/255.255.0.0
> > >
> > > ==>  eth2  [ 172.18.0.1.255.255.0.0]  ==>
> > > host-3 eth0= 172.18.0.2/255.255.0.0
> > >
> > > Thanks in advance for any guidance you can give
> > me.
> > >
> > > Johnny
> > >
> > 
> > I have a suggestion, use brctl
> > http://bridge.sourceforge.net/howto.html
> > 
> > and bind eth0, eth1, and eth2 to the same logical
> > device (br0) and then 
> > the three nics act like a three port bridge. You
> > only configure one 
> > ethernet device (br0) for all three hardware ports.
> > 
> > ed
> 
> 
> Thanks Ed,
> 
> I checked the url and wow, I didn't realize I could
> solve the problem with a bridge.  Very cool.
> I'm going to build a new machine over the next couple
> of days with 3+ nics... let ya know how it goes.
> Looking forward to it.
> 
> Johnny

For the cost of  switch (D-Link DSS-5+ 10/100 5 Port Switch, $25 at
Staples) vs the cost of more NICs, is it really worth it?  Especially if
you are burning up CPU cycles on the Firewall machine to do the
bridging.

If it's "just 'cause its there", go for it!

Bob...