Hello.

rc.ip_forward claims that we get rp_filter for free.
I'm finding that I have to enable it in sysctl.conf.

Is that the case for everyone, or is it just me?
I'm using Slackware 12, by the way.

I was exploring in this general vicinity today too and discovered, I think, the same thing. The documentation in rc.ip_forward claims that if you use IP forwarding then rp_filter is active. I assume that the easy way to tell if rp_filter is active is by examining the contents of /proc/sys/net/ipv4/conf/all/rp_filter. I see a "0". I think this means that my kernel is not using rp_filter, but I'm not quite sure how to check that it prevents IP spoofing.

I'm hoping someone more knowledgeable than I am on this topic can weigh in here.