Reversepath Filter doesn't work properly with illegal clustering settings

[Ry_I]

Hi,

I'm facing strange situation about Reversepath Filter.

My managing 2 nodes has each 2 NICs and I made a cluster by setting keepalived and macvlan on one of the NICs(both eth1) .
I set all responsible kernel parameter "rp_filter" as 0 because packets are passing asynmetrical route (inbound packets are via vrrp, and outbound are via eth1).

But somehow when rp_filter is reset to 1, contrary to expectation, networking is still alive.
I found I made a mistake to set clustering. I set keepalive on eth0 and set macvlan on eth1.
I know my settings are illegal, but it is strange that networking works properly although all rp_filter parameters are 1.

It would be helpful if someone tells me why this phenomenon occurs.

Thanks,

[TrevorH]

Is https://access.redhat.com/solutions/53031 any help?

[Ry_I]

Hi,

Thank you for reply.
I understood behavior is different between RHEL5 and 6/7 and reconfirmed how to set rp_filter parameters permanently.

My concern is that rp_filter settings might be invalid if Some network settings are set abnormally.
From a perspective of security, it is indispensable for me to understand how rp_filter works.

Thanks,