diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
index c7a8148..b2cf91e 100644
--- a/net/ipv4/Kconfig
+++ b/net/ipv4/Kconfig
@@ -50,6 +50,8 @@
 	  echo 1 > /proc/sys/net/ipv4/conf/all/rp_filter
 
 	  Note that some distributions enable it in startup scripts.
+	  For details about rp_filter strict and loose mode read
+	  <file:Documentation/networking/ip-sysctl.txt>.
 
 	  If unsure, say N here.