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Date:      Wed, 24 Jan 2007 11:12:13 -0500
From:      "Michael W. Oliver" <>
To:        Arone Silimantia <>
Subject:   Re: ipfw pipe show .... clarification, please ...
Message-ID:  <>
In-Reply-To: <>
References:  <>

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On 2007-01-23T16:37:13-0800, Arone Silimantia wrote:
> I set up a dummynet pipe with this sequence of commands:
> sysctl -w net.inet.ip.fw.one_pass=0
> ipfw pipe 1 config bw 16Mbit/s
> ipfw add 10000 pipe 1 all from any to any
> So far so good.  Works great.  However, when I look at the pipe
> itself, with this command:
> ipfw pipe show 1
> I see this:
> # ipfw pipe show 1
> 00001:  16.000 Mbit/s    0 ms   50 sl. 1 queues (1 buckets) droptail
>    mask: 0x00 0x00000000/0x0000 -> 0x00000000/0x0000
> BKT Prot ___Source IP/port____ ____Dest. IP/port____ Tot_pkt/bytes Pkt/Byte Drp
>  0 tcp  2970975653 2649647615805  2 2992 10414733
> I would like to clarify a few things...
> First, the ipfw pipe creation command I ran is not (as far as I can
> tell) TCP specific, and further, my ipfw rule says "any to any" - but
> when I look at the pipe, it has a protocol specified (TCP) and
> further, has a port number (22).  I want to throttle ALL IP traffic,
> not just TCP, and certainly not just port 22.
> What am I doing wrong ?

I think what you are seeing is just the latest user of the rule, and it
happened to be that SSH connection.  Since you are using an all-zeros
mask, all traffic will fall into the same bucket and as such you will
only see the latest flow/conversation/stream that used the rule.  I
could be wrong here, and would like clarification if so.

> Second, there are seven headings (from BKT at the left to Drp on the
> right) but underneath those seven headings are _9_ values.  What I
> really want to know is how many packets I am droppinig ... but I can't
> tell which of the fields are the "dropped" - I assume it is the final
> number .. if so, what is that measured in ?  Packets ?

Yes, the drops are listed in number of packets, and what you are seeing
as nine fields is broken down as follows:

Source IP/port
Dest. IP/port

The "Tot_pkt/bytes" and "Pkt/Byte" values are split, even though the
headings are not.  Not very intuitive, and actually quite ugly.  Again,
I am no expert and would like clarification if I am wrong.

Personally, if I could code at all, I would try to whip up a patch that
would do something like this....

00001:  16.000 Mbit/s    0 ms   50 sl. 1 queues (1 buckets) droptail
    mask: 0x00 0x00000000/0x0000 -> 0x00000000/0x0000
 BKT 0
  Prot: TCP
  Total (pkts/bytes): 2970975653/2649647615805
  Current (pkts/bytes): 2/2992
  Drops: 10414733

> Finally, why am I dropping any packets ?  My total traffic is 5-7
> Mbits/s on average ... I don't see why I would be dropping any packets
> at all ... are they being dropped because the system can't keep up, or
> are they being dropped because I am hitting the throttle limit and it
> drops everything above that ?

I think you are dropping packets because you are exceeding the pipe

I am no expert on this stuff, just offering some possible answers to
your questions.

Have fun!

- -- 
Mike Oliver, KI4OFU
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