Subject: pf: pass in quick to port 25 still getting blocks

[David DeSimone]

Len Conrad <lconrad at Go2France.com> wrote:
>
> pass in quick on $ext_if inet proto tcp from any to $ext_if port smtp keep state

Be aware that there is an implied "flags S/SA" added to your rule, so it
only matched initial SYN packets.

> and the last rule is:
> 
> block in log on $ext_if from any to $ext_if,  which logs as: 

> in spite of the pass in smtp, rule 33 is still blocking several 1000 SMTP accesses/day, eg:
> 
> rule 33/0(match): block in on em0: 74.120.242.172.57093 > x.x.x.x.25: . ack 50 win 46 <nop,nop,timestamp 727203637 3292309473>
> 
>  rule 33/0(match): block in on em0: 94.179.232.111.8364 > x.x.x.x.25: P 0:6(6) ack 1 win 65438

The packets shown here are not SYN packets, so they fail to match the
early rule.  They are supposed to be matched by the connection state
which is built, but for some reason they are not matching.  Are your
state entries expiring early for some reason?

You may want to add "log" to the early pass rule, and then you can
compare the timestamp between when the initial SYN arrived for a
connection, and the later block occurred for a packet in the middle of
the connection.

-- 
David DeSimone == Network Admin == fox at verio.net
  "I don't like spinach, and I'm glad I don't, because if I
   liked it I'd eat it, and I just hate it." -- Clarence Darrow


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