Clusters replying from same IP address without a NAT?

klacke <>
Wed Aug 18 23:11:17 CEST 2004

On Wed, Aug 18, 2004 at 03:39:16PM +0200, Lennart Öhman wrote:
>    A slightly off the topic question...
>    Anyone familiar with the possibility to have a second "hidden"
>    IP address associated with a physical network interface in
>    Solaris style UNICIES. Hidden in the sence that it does not
>    answer ARP questions, in order to not confuse routers since I
>    plan to have several such hidden interfaces on the same network
>    with the same IP address.

The way to go about this in linux is to use a dummy interface,

[]~ > modprobe dummy

[]~ > ip addr add dev dummy0

[]~ > ip addr show
1: eth0: <BROADCAST,MULTICAST,NOTRAILERS,UP> mtu 1500 qdisc \
          pfifo_fast qlen 1000
    link/ether 00:0a:e6:6c:f2:96 brd ff:ff:ff:ff:ff:ff
    inet brd scope global eth0
2: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet scope host lo
3: eth1: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether 00:50:22:39:00:76 brd ff:ff:ff:ff:ff:ff
    inet brd scope global eth1
    inet brd scope global secondary eth1:0
4: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop 
    link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
    inet scope global dummy0

This way, packets destined to which goes through this box, 
(somehow, either because the box is inline, or packets get REDIRECTED
to it) will be terminated on the box and not routed further.

Solaris, I know nothing about, but I bet it works pretty similar.


Claes Wikstrom                        -- Caps lock is nowhere and                  -- everything is under control          

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