Hi All:
When I test linux kernel 2.6.9-34, and find that kernel statistics
about ipInHdrErrors which exsits in file /proc/net/snmp doesn't increase
correctly. The criteria conform to RFC2011:
ipInHdrErrors OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of input datagrams discarded due to errors in
their IP headers, including bad checksums, version number
mismatch, other format errors, time-to-live exceeded, errors
discovered in processing their IP options, etc."
When kernel receives an IP packet containing error protocol in IP
header, kernel doesn't increase this counter "ipInHdrErrors". Also, when
kernel receives an IP packet and need to forward, but TTL=1 or TTL=0,
kernel just sends an ICMP packet to inform the sender TTL count
exceeded, and doesn't increase this counter.
The patch for this problem is shown as the following:
diff -ruN old/net/ipv4/ip_forward.c new/net/ipv4/ip_forward.c
--- old/net/ipv4/ip_forward.c 2006-05-10 10:43:30.000000000 +0800
+++ new/net/ipv4/ip_forward.c 2006-05-12 15:06:57.000000000 +0800
@@ -120,6 +120,7 @@
too_many_hops:
/* Tell the sender its packet died... */
+ IP_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
icmp_send(skb, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL, 0);
drop:
kfree_skb(skb);
diff -ruN old/net/ipv4/ip_input.c new/net/ipv4/ip_input.c
--- old/net/ipv4/ip_input.c 2006-05-10 10:43:31.000000000 +0800
+++ new/net/ipv4/ip_input.c 2006-05-12 15:07:27.000000000 +0800
@@ -249,6 +249,7 @@
if (!raw_sk) {
if (xfrm4_policy_check(NULL,
XFRM_POLICY_IN, skb)) {
IP_INC_STATS_BH(IPSTATS_MIB_INUNKNOWNPROTOS);
+
IP_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
icmp_send(skb,
ICMP_DEST_UNREACH,
ICMP_PROT_UNREACH, 0);
}
Signed-off-by: Wei Dong <[EMAIL PROTECTED]>
Regards
Wei Dong
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