Date: Thu, 8 May 2014 09:38:16 +0200 From: Luigi Rizzo <rizzo@iet.unipi.it> To: bycn82 <bycn82@gmail.com> Cc: "freebsd-ipfw@freebsd.org" <freebsd-ipfw@freebsd.org>, Freddie Cash <fjwcash@gmail.com> Subject: Re: feature of `packet per second` Message-ID: <20140508073816.GB64368@onelab2.iet.unipi.it> In-Reply-To: <536AD941.9090102@gmail.com> References: <5360F1F4.9060808@gmail.com> <5361105C.1040203@freebsd.org> <53611738.8010103@gmail.com> <CAOjFWZ4zRUmcjG-r--OqoGEWcSZoWhtTykgAAHzCjoEWsMVS9g@mail.gmail.com> <53611EB1.4000406@gmail.com> <CA%2BhQ2%2BhjjS=AXVdnaEdFOKY1DqiLuX9iP0gy3wo6FbwnEdq_Qw@mail.gmail.com> <5364E097.9020106@gmail.com> <CA%2BhQ2%2BgXC9uNdtH1VCGa%2Bs1dPNWjErC9qfgXmEnfQ4SQ6Rnz_g@mail.gmail.com> <536AD13B.6080907@gmail.com> <536AD941.9090102@gmail.com>
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On Thu, May 08, 2014 at 09:09:21AM +0800, bycn82 wrote:
> On 5/8/14 8:35, bycn82 wrote:
> > On 5/4/14 1:19, Luigi Rizzo wrote:
> >>
> >>
> >>
> >> On Sat, May 3, 2014 at 2:27 PM, bycn82 <bycn82@gmail.com
> >> <mailto:bycn82@gmail.com>> wrote:
> >>
> >> On 5/2/14 16:59, Luigi Rizzo wrote:
> >>>
> >>>
> >>>
> >>> On Wed, Apr 30, 2014 at 6:02 PM, bycn82 <bycn82@gmail.com
> >>> <mailto:bycn82@gmail.com>> wrote:
> >>>
> >>>
> >>> fjwcash@gmail.com <mailto:fjwcash@gmail.com>
> >>> <mailto:fjwcash@gmail.com <mailto:fjwcash@gmail.com>>
> >>>
> >>> Thanks for your reply, and it is good to know the sysctl
> >>> for ICMP.
> >>>
> >>> finally it works.I just added a new `action` in firewall and
> >>> it is called `pps`, that means it can be generic purpose
> >>> while the net.inet.icmp.icmplim is only for ICMP traffic.
> >>>
> >>> the usage will be like below
> >>>
> >>> root@F10:/usr/src/sbin/ipfw # .*/ipfw add pps 1 icmp from
> >>> any to any*
> >>> 00100 pps 1 icmp from any to any
> >>> root@F10:/usr/src/sbin/ipfw # ./ipfw show
> >>> 00100 9 540 pps 1 icmp from any to any
> >>> 65535 13319 1958894 allow ip from any to any
> >>> root@F10:/usr/src/sbin/ipfw #
> >>>
> >>>
> >>> ???hi,
> >>> as julian said it would be great if you would like to share your
> >>> code
> >>> so we can integrate it in future ipfw releases.
> >>> Once again citing Julian, dummynet is a bit of a superset of pps but
> >>> not exactly, so i see value in the additional feature.
> >>>
> >>> One thing ???to keep in mind in the implementation:
> >>>
> >>> the burst size used for limiting is an important parameter that
> >>> everyone forgets. 1 pps is basically "don't bother me".
> >>> 1000 pps could be "1000 packets every fixed 1-sec interval"
> >>> or "1 packet every ms" or (this is more difficult)
> >>> "20 pkt in the last 50ms interval".
> >>>
> >>> If i were to implement the feature i would add two parameters
> >>> (burst, I_max) with reasonable defaults and compute the internal
> >>> interval and max_count as follows
> >>> if (burst > max_pps * I_max)
> >>> burst = max_pps * I_max; // make sure it is not too large
> >>> else if (burst < max_pps / HZ)
> >>> burst = max_pps * HZ; // nor too small
> >>> max_count = max_pps / burst;
> >>> interval = HZ * burst / max_pps;
> >>> count = 0; // actual counter
> >>>
> >>> then add { max_count, interval, timestamp, count } to the rule
> >>> descriptor.
> >>> On incoming packets:
> >>>
> >>> if (ticks >= r->interval + r->timestamp) {
> >>> r->timestamp = r->ticks;
> >>> r->count = 1;
> >>> return ACCEPT;
> >>> }
> >>> if (r->count > r->max_count)
> >>> return DENY;
> >>> r->count++;
> >>> return ACCEPT;
> >>>
> >>> cheers
> >>> luigi
> >>>
> >> Hi Luigi,
> >> You are right, it will be more generic if provide two parameters
> >> as you described,
> >> But this PPS feature should not be used to control the traffic
> >> rate, the dummynet you provided is the correct way.
> >> So I am thinking in what kind of scenario, people need this PPS
> >> feature?
> >> in my opinion, people will use PPS only when they want to limit
> >> the connections/transactions numbers. ( already have limit
> >> command to limit the connections)
> >> So I think provide a simple PPS feature is good enough, and we
> >> can improve it if someone complaint on this.
> >>
> >>
> >> ???pps has a strong reason to exist because it is a lot cheaper
> >> than a dummynet pipe, and given its pur???pose is to police
> >> traffic (icmp, dns requests, etc) which should not even
> >> get close to the limit which is set, I think it is
> >> a completely reasonable feature to have.
> >>
> >> Given that the above code is the complete implementation
> >> with the two parameters (burst and interval) there is no
> >> reason not to use them, at least internally.
> >>
> >> Then you could choose not to expose them as part of the
> >> user interface (though since you are implementing a new
> >> option from scratch, it is completely trivial to
> >> parse 1, 2 or 3 arguments and set defaults for the others).
> >>
> >> cheers
> >> luigi
> > OK, PPS with 2 parameters , it is done,
> > But how to get the current time in millisecond?
> > any recommendation?
> In order to get the millisecond, i tried to include the timeb.h but i
> met below
FreeBSD has a global kernel variable called ticks which increments
(roughly) HZ times per second and is all you need for this
kind of coarse estimates.
In linux there is something similar (jiffies maybe ?),
and the code to build ipfw on linux does some reasonable
mapping.
The code i posted is, i believe, complete and contains
all the details.
cheers
luigi
>
> n file included from
> /usr/src/sys/modules/ipfw/../../netpfil/ipfw/ip_fw2.c:42:
> @/sys/timeb.h:42:2: error: "this file includes <sys/timeb.h> which is
> deprecated"
> [-Werror,-W#warnings]
> #warning "this file includes <sys/timeb.h> which is deprecated"
> ^
> any replacement for timeb.h
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