[Coco] OT: Networking problem

Gene Heskett gheskett at wdtv.com
Wed Nov 28 21:03:16 EST 2012


On Wednesday 28 November 2012 20:50:43 Gene Heskett did opine:

I know, its poor form to reply to one own posts, but this one has way too 
many typu's :(

> On Wednesday 28 November 2012 20:09:51 David Hazelton did opine:
> > Not to ask a stupid question, but Does your ISP allow their DSL Modem
> > to have multiple IPs.
> > Working for Comcast, the cable modem only passes 1 IP.  so what you
> > are doing is not possible by going off the dsl modem.
> 
> Several machines on one outside IP address is absolutely not a problem
> David.  There is no crosstalk between the machines even when the 2 out
> in the shop are both installing the latest updates to the 10.04.4
> installs I have on 4 machines here, and which could just as easily be
> 253 machines.
> 
> Its called NAT, for Native Address Translation.  If your router cannot
> do that, toss it in the bin and get one that will as its been a 

s/atd/standard/

> feature of most for over 15 years that I know of.
> 
> I've had 6 or seven in that position between the cable or dsl modem and
> an 8 port switch for well over a decade now.  The best I have found are
> all running some version of dd-wrt for software, and I am currently using
> a Buffalo NFinity Hi Power, which comes with a broken, customized
> version of dd-wrt.  But their banners covered up some of the functions,
> which was the brokenness so it got reflashed to the real dd-wrt.
> 
> All machines on the on-property net, coming off that 8 port switch, are
> using hard coded addresses in 192.168.nn.xx range, set the
> /etc/hosts file except the lappy, a file that is common to all the
> machines, with only that machines hostname differentiating between
> them.
> 
> The lappy gets an address from the dhcp server in the router.  And it
> all Just Works(TM).  Any machine plugged into the switch can do
> anything it wants in the way of net access, with complete isolation
> between the machines.
> 
> OTOH NFS mounts between the main 3 machines works as expected, as does
> ssh -Y access between them.
> 
> > On 11/26/2012 6:59 PM, Aaron Banerjee wrote:
> > > This is a little off-topic, but is something eople here probably
> > > have more experience with than I do.
> > > 
> > > I'm trying to "partition" off my network into multiple networks
> > > (e.g. for experimental purposes/parental control/etc).  I have a
> > > DSL modem and a router.  I thought the following configuration
> > > would work, but it doesn't.
> > > 
> > >                       ----
> > >                       
> > >                       |   | <--------------------------> {other
> > >                       |   | device
> > > 
> > > with static 192.168.1.n IP}
> > > {internet}  <-------> |   |   "1.2.168.1.x" network
> > > 
> > >                       |   |    static IPs                ----
> > >                       |   | 
> > >                       |   | <--------------------------> | R |
> > > 
> > > "192.168.0.y" network (using DCHP from router)
> > > 
> > >                       ----                               | O |
> > >                    
> > >                    DSL Modem                             | U |
> > > 
> > > <------------> device 1
> > > 
> > >                   192.168.1.1                            | T |
> > > 
> > > <------------> device 2
> > > 
> > >                                                          | E |
> > > 
> > > <------------> device 3
> > > 
> > >                                                          | R |
> > >                                                          
> > >                                                          ----
> > >                                             
> > >                                             192.168.1.101 /
> > >                                             192.168.0.1
> > >                                             
> > >                                                    netmask 
255.255.0.0
> > > 
> > > Sorry about the '80s era graphics, but I didn't want to have to
> > > attach a file -- and besides, I'm from the '80s era (at least when
> > > it comes to computers).

Spring chicken... :)
 
> > > 1.  I'd like to have the device 1,2,3 be able to "ping" or summarily
> > > see the modem.  I think this should work, but it doesn't.  What did
> > > I do wrong (or not do right)?
> 
> You'll need a secondary interface, setup on the same hardware, something
> like an eth0.1.  Its in the man pages and a bit lengthy for a mailing
> list post.
> 
> As for a connection between the "0.xx addresses, and the "1.xx', look up
> the keyword "bridge", which will wire up a connection between those 2
> nets.
> 
> > > The router's address to its clients is 192.168.0.1.

Because its so common, I don't use either of those two class D's here, 
which explains the paranoia about the nn in my examples above.

> > > It is
> > > statically set to 192.168.1.101 for purposes of the modem (which
> > > doesn't use DCHP).  The router then uses its own DCHP to doll out
> > > addresses to its client as it sees fit (in particular it starts
> > > with .100).
> > > 
> > > For experimental purposes, I took down the firewall completely in
> > > order to eliminate that as a source of the problem.  I'm getting a
> > > "no route to host" when I ping 192.168.1.1 from the devices on the
> > > "0" net (e.g. device 1, 2, or 3).  I don't have "ping" blocked at
> > > the modem or router just for good measure, and don't think I'm
> > > masking out the "1".  Even a few desperado attempts using DMZs
> > > didn't work, and eventually messed up my network until I could undo
> > > all that I had done.
> > > 
> > > I'm obviously missing something very simple and elementary and will
> > > probably kick myself when someone points it out to me.  I just
> > > haven't done this type of thing in a long while.
> > > 
I think the keyword is "bridge". In dd-wrt, its device br0, and I believe 
its possible to have more than one set in dd-wrt. But all I am using is the 
default br0, I've not felt the need for a br1 yet with my simple only a 
handful of machines network.

Cheers, Gene
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