[Winpcap-users] Slow sending?

New accounts at sandmik.net accounts at sandmik.net
Fri Mar 31 08:19:31 GMT 2006


Hey guys, thanks a lot for everybody that helped.

pcap_setmintocopy did the trick.
 From 2 seconds ping time, down to < 10 msec.

They should mention it in the manual in the section of sending packets 
and not just in the exported function section.

Thanks.

New accounts at sandmik.net wrote:

> Oh one more thing,
>
>    I am sure about the results as I am testing it by pinging two 
> machines (that are arp poisoned) on the network.
>
> The ping is taking around 2 seconds, after some debugging and testing 
> with ethereal, I found out that each one send there is a delay of 
> around 1 second, hence the 2 seconds in the ping.
>
>    Thank you again.
>
> Loris Degioanni wrote:
>
>> As far as I know, libdnet and most of the other traffic injection 
>> libraries end up using WinPcap for actual transmission, so switching 
>> to them is not going to help a lot.
>>
>> First of all, a delay of 1 second seems quite huge, even if a system 
>> call per packet is issued. Are you sure the delay is in transmission 
>> and not in reception?
>> A Rx 1 sec delay is normal if you don't set a low timeout and mintocopy.
>>
>> Second: I know of several winpcap-based arp poisoners, and they 
>> appear to work pretty well. You may want to look at their sources to 
>> learn how they achieve that. For example, look at 
>> http://ettercap.sourceforge.net for a very well known one. You'll 
>> find more of them at http://www.winpcap.org/misc/links.htm#tools.
>>
>> Loris
>>
>>
>> New accounts at sandmik.net wrote:
>>
>>> Thank you loris for trying to help me.
>>>
>>> I have used the queue version as well but I did not get higher 
>>> performance, I believe because everytime I call this function I only 
>>> have one packet to send. My ARP Poisoner has to relay packets as 
>>> soon as they come... So I have this incredible delay.
>>>
>>> I think I will be looking into other means (maybe other libraries) 
>>> of sending the packets (like libdnet, just found it on the web).
>>>
>>> If you have used any other mean to send ethernet packets, I would 
>>> appreciate the help.
>>>
>>> Thanks again.
>>>
>>> Loris Degioanni wrote:
>>>
>>>> If you want to increase the Tx performance, use buffered send 
>>>> functions(pcap_sendqueue*). pcap_sendpacket() does a context switch 
>>>> per packet, that's the reason why it's so slow.
>>>>
>>>> Loris
>>>>
>>>>
>>>> Accounts wrote:
>>>>
>>>>> Hi Everybody.
>>>>>
>>>>>    I am using WinPCap to do active redirection of packets. Everything
>>>>> is working very well except I have one problem.
>>>>>
>>>>> WinPCap seems to be very slow to send the packets?
>>>>>
>>>>> I checked my code from the time I receive the packet to my code until
>>>>> the time I call pcap_sendpacket, there is less than 1 ms so I know 
>>>>> the
>>>>> problem
>>>>> is not a bottleneck in my code. However looking at ethereal and doing
>>>>> some pinging tests. It looks like after I call pcap_sendpacket it is
>>>>> taking up to 1 second to actually go out.
>>>>>
>>>>>    Any ideas?!
>>>>>
>>>>>    Any help would be appreciated.
>>>>>
>>>>>    And also I tried to use send queues but the same problem.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
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>>>>> Winpcap-users at winpcap.org
>>>>> https://www.winpcap.org/mailman/listinfo/winpcap-users
>>>>>
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>
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