tcp: Change possible SYN flooding messages
"Possible SYN flooding on port xxxx " messages can fill logs on servers.
Change logic to log the message only once per listener, and add two new
SNMP counters to track :
TCPReqQFullDoCookies : number of times a SYNCOOKIE was replied to client
TCPReqQFullDrop : number of times a SYN request was dropped because
syncookies were not enabled.
Based on a prior patch from Tom Herbert, and suggestions from David.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index b14ec7d..4bfad5d 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -254,6 +254,8 @@
SNMP_MIB_ITEM("TCPDeferAcceptDrop", LINUX_MIB_TCPDEFERACCEPTDROP),
SNMP_MIB_ITEM("IPReversePathFilter", LINUX_MIB_IPRPFILTER),
SNMP_MIB_ITEM("TCPTimeWaitOverflow", LINUX_MIB_TCPTIMEWAITOVERFLOW),
+ SNMP_MIB_ITEM("TCPReqQFullDoCookies", LINUX_MIB_TCPREQQFULLDOCOOKIES),
+ SNMP_MIB_ITEM("TCPReqQFullDrop", LINUX_MIB_TCPREQQFULLDROP),
SNMP_MIB_SENTINEL
};