Re: problem with interfaces

[Robert Elz <kre%munnari.OZ.AU@localhost>]

    Date:        Mon, 23 Feb 2015 21:47:41 -0500
    From:        Ezequiel Reyes Aragon <ezequiel%ecaribe.co.cu@localhost>
    Message-ID:  <54EBE64D.7050306%ecaribe.co.cu@localhost>

  | I used sysctl in the virtual gateway machine to set ip forwarding = 1.
  | Is there something else that needs to be done?

Depends whether you want network 10 visible through the rest of your network
or not (to all the places you want your network 10 addresses systems to
be able to reach).

If you do, you need to set up routing (routing protocol, and/or default 
routing or static routes) in the 192.168 network space so that packets for
10.0.0/24 get returned to your gateway PC.   If there is a NAT between the
192.168 and the internet (which there must be, if it is connected) and if
you want the internal systems to reach the internet, then that NAT config
would need to know to translate net 10 as well as 192.168 addresses.

If not, then you need to configure the gateway system to use NAT, and have
it translate the network 10 addresses into its own 192.168 address (whether
or not there is another NAT connecting to the internet becomes irrelevant
then.)

In either case, the thing to remember is that you not only need to figure
out the method by which your internal systems get packets out to whatever
parts of the net you want them to reach, but how the peer systems successfully
get replies back to the internal systems.

Of the two methods, if you don't have constraints, the first is more flexible
and will likely work better - but it requires config access to systems other
than the ones you have mentioned (at least whatever is the default router for
the rest of the 192.168 hosts).   The second you can make work using only
config on your gateway PC (the one with addresses both on net 10 and 192.168).

kre

ps: incidentally it makes no difference at all whether the systems in question
are real hardware of virtual hosts.