Q: When will "ip_forward per interface" flag in /proc used?

[Peter Bieringer <pb@xxxxxxxxxxxx>]

Hi,

surly a dump question, but a look into the source code gave me no answer.

There exists in newer kernel 2.1.9x+(?) an IP forwarding switch
(all/default/per device)

My question is now, when will the information "per interface" used:

( ) decide forwarding packets coming *from* this interface
( ) decide forwarding packets sending *to* this interface
( ) in both cases

TIA,
        Peter