Subject: Re: vnet problem (bug? feature?)

From: David Ahern <[email-masked]>
Date: Mon, 16 Feb 2015 08:30:12 -0700

On 2/16/15 3:13 AM, Toerless Eckert wrote:
> I fail to find a good reference explaining why linux would default to
> rp_filtering = 1 (more appropriate for routers) even if forwarding defaults to 0
> (more appropriate for multi-homed hosts).

It's a userspace default. For Fedora/Red Hat based systems see 
/etc/sysctl.conf (older releases) and /usr/lib/sysctl.d/50-default.conf 
(newer ones).

I recall it defaulting to 1 in the early 2000's so it has been that way 
for a long time.

 From Documentation/networking/ip-sysctl.txt:

rp_filter - INTEGER
...
         Default value is 0. Note that some distributions enable it
         in startup scripts.

David