[TCP]: SNMPv2 tcpAttemptFails counter error
Refer to RFC2012, tcpAttemptFails is defined as following:
tcpAttemptFails OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of times TCP connections have made a direct
transition to the CLOSED state from either the SYN-SENT
state or the SYN-RCVD state, plus the number of times TCP
connections have made a direct transition to the LISTEN
state from the SYN-RCVD state."
::= { tcp 7 }
When I lookup into RFC793, I found that the state change should occured
under following condition:
1. SYN-SENT -> CLOSED
a) Received ACK,RST segment when SYN-SENT state.
2. SYN-RCVD -> CLOSED
b) Received SYN segment when SYN-RCVD state(came from LISTEN).
c) Received RST segment when SYN-RCVD state(came from SYN-SENT).
d) Received SYN segment when SYN-RCVD state(came from SYN-SENT).
3. SYN-RCVD -> LISTEN
e) Received RST segment when SYN-RCVD state(came from LISTEN).
In my test, those direct state transition can not be counted to
tcpAttemptFails.
Signed-off-by: Wei Yongjun <yjwei@nanjing-fnst.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 0ccb7cb..624e2b2 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -589,8 +589,10 @@
/* RFC793: "second check the RST bit" and
* "fourth, check the SYN bit"
*/
- if (flg & (TCP_FLAG_RST|TCP_FLAG_SYN))
+ if (flg & (TCP_FLAG_RST|TCP_FLAG_SYN)) {
+ TCP_INC_STATS_BH(TCP_MIB_ATTEMPTFAILS);
goto embryonic_reset;
+ }
/* ACK sequence verified above, just make sure ACK is
* set. If ACK not set, just silently drop the packet.