ipv4: Clarify in docs that accept_local requires rp_filter.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 3 deletions

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 99d0e0504d6e..47b6c79e9b05 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -857,9 +857,14 @@ accept_source_route - BOOLEAN
                 FALSE (host)
 
 accept_local - BOOLEAN
-        Accept packets with local source addresses. In combination with
-        suitable routing, this can be used to direct packets between two
-        local interfaces over the wire and have them accepted properly.
+        Accept packets with local source addresses. In combination
+        with suitable routing, this can be used to direct packets
+        between two local interfaces over the wire and have them
+        accepted properly.
+
+        rp_filter must be set to a non-zero value in order for
+        accept_local to have an effect.
+
         default FALSE
 
 route_localnet - BOOLEAN