Re: virtual nic

[Pietro Cagnoni <pcagnoni@mclink.net>]

> Hello,
> 
> is it possible to set up a virtual NIC and network? I would like to do
> this:
> eth0 <- iptable filter -> virtual <- more iptables -> rest of the system.
> 
> I want to filter out some traffic because I only want to monitor some of
> the traffic.

see /usr/src/linux/Documentation/networking/alias.txt

the most interesting part is:

o For IP aliasing you must have IP_ALIAS support included by static
  linking.

o Alias creation.
  Alias creation is done by 'magic' iface naming: eg. to create a
  200.1.1.1 alias for eth0 ...

    # ifconfig eth0:0 200.1.1.1  etc,etc....
                   ~~ -> request alias #0 creation (if not yet exists)
for eth0
    and routing stuff also ...
    # route add -host 200.1.1.1 dev eth0:0  (if same IP network as
                                            main device)

    # route add -net 200.1.1.0 dev eth0:0   (if completely new network
wanted
                                            for eth0:0)

o Alias deletion.
  Also done by shutting the interface down:

    # ifconfig eth0:0 down
                 ~~~~~~~~~~ -> will delete alias