On 5/4/14 1:19, Luigi Rizzo wrote:
On Sat, May 3, 2014 at 2:27 PM, bycn82 <byc...@gmail.com
<mailto:byc...@gmail.com>> wrote:
On 5/2/14 16:59, Luigi Rizzo wrote:
On Wed, Apr 30, 2014 at 6:02 PM, bycn82 <byc...@gmail.com
<mailto:byc...@gmail.com>> wrote:
fjwc...@gmail.com <mailto:fjwc...@gmail.com>
<mailto:fjwc...@gmail.com <mailto:fjwc...@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 purpose 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?
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