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List:       ipfilter
Subject:    RE: Dropped Packets - Help please!
From:       Erik Huizing <erik.huizing () sjrb ! ca>
Date:       2006-02-01 22:39:48
Message-ID: B4EA36D3437761448FA9C3252FCC71245077FD () PRDCG4EXVW01-1 ! OSS ! PRD
[Download RAW message or body]

We've got a few servers where we see similar behaviour (running 3.4.31 on solaris 9)

Feb  1 14:25:03 ns1.ht ipmon[92]: [ID 702911 local0.warning] 14:25:03.523152 hme0 \
                @0:24 b xxx.xxx.xxx.248,35931 -> yyy.yyy.yyy.50,8443 PR tcp len 20 52 \
                -AF IN
Feb  1 14:25:05 ns1.ht ipmon[92]: [ID 702911 local0.warning] 14:25:05.562480 hme0 \
                @0:24 b xxx.xxx.xxx.248,35931 -> yyy.yyy.yyy.50,8443 PR tcp len 20 \
                191 -AFP IN
Feb  1 14:25:12 ns1.ht ipmon[92]: [ID 702911 local0.warning] 14:25:12.602694 hme0 \
                @0:24 b xxx.xxx.xxx.248,35931 -> yyy.yyy.yyy.50,8443 PR tcp len 20 \
                191 -AFP IN
Feb  1 14:25:26 ns1.ht ipmon[92]: [ID 702911 local0.warning] 14:25:26.685533 hme0 \
                @0:24 b xxx.xxx.xxx.248,35931 -> yyy.yyy.yyy.50,8443 PR tcp len 20 \
                191 -AFP IN
Feb  1 14:25:54 ns1.ht ipmon[92]: [ID 702911 local0.warning] 14:25:54.842143 hme0 \
                @0:24 b xxx.xxx.xxx.248,35931 -> yyy.yyy.yyy.50,8443 PR tcp len 20 \
                191 -AFP IN
Feb  1 14:25:58 ns1.ht ipmon[92]: [ID 702911 local0.warning] 14:25:58.584418 hme0 \
                @0:24 b xxx.xxx.xxx.248,35931 -> yyy.yyy.yyy.50,8443 PR tcp len 20 40 \
                -R IN
Feb  1 14:26:36 ns1.ht ipmon[92]: [ID 702911 local0.warning] 14:26:36.705447 hme0 \
@0:24 b 211.126.199.141,35642 -> 64.59.168.50,49153 PR udp len 20 38 IN

and with 
pass in quick proto tcp from xxx.xxx.xxx.0/23 to any port = 8443 flags S keep state \
keep frags

 in the rules file.

state table stats on said box:
IP states added:
        20323 TCP
        19414788 UDP
        0 ICMP
        45920495 hits
        39668302 misses
        237297 maximum
        0 no memory
        2930 bkts in use
        4013 active
        19411029 expired
        20069 closed

IP states added:
        20323 TCP
        19414788 UDP
        0 ICMP
        45920495 hits
        39668302 misses
        237297 maximum
        0 no memory
        2930 bkts in use
        4013 active
        19411029 expired
        20069 closed

thanks in advance,

-----Original Message-----
From: owner-ipfilter@coombs.anu.edu.au
[mailto:owner-ipfilter@coombs.anu.edu.au]On Behalf Of Jim Sandoz
Sent: January 27, 2006 8:37 AM
To: Barb, Duane
Cc: ipfilter@coombs.anu.edu.au
Subject: Re: Dropped Packets - Help please!


Barb, Duane wrote:
> I'm getting dropped packets:
> 
> [ID 702911 local0.warning] 08:45:14.146313 bge0 @0:2 b x.x.x.x,30404 ->
> x.x.x.x,443 PR tcp len 20 40 -AR IN

duane,

this is a blocked packet, not a dropped packet.
it is arriving at your external interface and being blocked.
note, the line above indicates that the ACK+RST flags are set.

my best guess is that this tuple was once in the state table,
but the connection is already torn down, (i.e., ipf's state
table has deleted the entry), and this packet is thus bouncing
off of the firewall and being logged as a blocked packet.

in other words, it is a packet not associated with a current
state entry, and also not one that initiates a state entry
by the following rule (since the flags don't match up):
 > pass in quick on bge0 proto tcp from any to x.y.z.122/32 port = 443
 > flags S keep state keep frags
and therefore it is blocked.

seeing the above log entry, assuming you are not having other
issues, is no cause for alarm.  more than likely it is due to
the interaction of the web server/client connection keepalive
mechanisms and ipf's state table expiry times.

jim


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