ipv4: add LINUX_MIB_IPRPFILTER snmp counter

Christoph Lameter mentioned that packets could be dropped in input path
because of rp_filter settings, without any SNMP counter being
incremented. System administrator can have a hard time to track the
problem.

This patch introduces a new counter, LINUX_MIB_IPRPFILTER, incremented
each time we drop a packet because Reverse Path Filter triggers.

(We receive an IPv4 datagram on a given interface, and find the route to
send an answer would use another interface)

netstat -s | grep IPReversePathFilter
    IPReversePathFilter: 21714

Reported-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/snmp.h b/include/linux/snmp.h
index 52797714ade7..ebb0c80ffd6e 100644
--- a/include/linux/snmp.h
+++ b/include/linux/snmp.h
@@ -229,6 +229,7 @@ enum
         LINUX_MIB_TCPBACKLOGDROP,
         LINUX_MIB_TCPMINTTLDROP, /* RFC 5082 */
         LINUX_MIB_TCPDEFERACCEPTDROP,
+        LINUX_MIB_IPRPFILTER, /* IP Reverse Path Filter (rp_filter) */
         __LINUX_MIB_MAX
 };