Bug 5016

Summary: rp_filter documentation error in Kconfig
Product: Networking Reporter: Adrian Buciuman (adibuciuman)
Component: OtherAssignee: Arnaldo Carvalho de Melo (acme)
Status: REJECTED DUPLICATE    
Severity: low    
Priority: P2    
Hardware: i386   
OS: Linux   
Kernel Version: 2.6 2.4 Subsystem:
Regression: --- Bisected commit-id:

Description Adrian Buciuman 2005-08-07 11:46:26 UTC
rp_filter is off by _kernel_ default.
(Some distibutions turn it on in startup scripts).

The folowing text from net/ipv4/Kconfig is confusing.(It seems one distribution 
maintainer thinks rp_filter is on by kernel default)

"config IP_ADVANCED_ROUTER
[..........]
If you turn on IP forwarding, you will also get the rp_filter, which
automatically rejects incoming packets if the routing table entry
for their source address doesn't match the network interface they're
arriving on. This has security advantages because it prevents the
so-called IP spoofing, however it can pose problems if you use
asymmetric routing (packets from you to a host take a different path
than packets from that host to you) or if you operate a non-routing
host which has several IP addresses on different interfaces. To turn
rp_filter off use:

echo 0 > /proc/sys/net/ipv4/conf/<device>/rp_filter
or
echo 0 > /proc/sys/net/ipv4/conf/all/rp_filter"

In 2.4 the error is in Documentation/Configure/help. Please fix this too.

Thanks.
Comment 1 Adrian Bunk 2005-08-07 12:45:23 UTC

*** This bug has been marked as a duplicate of 5015 ***