[prev in list] [next in list] [prev in thread] [next in thread]
List: winpcap-users
Subject: Re: [Winpcap-users] Where does the Winpcap
From: John Wang <locationdev () gmail ! com>
Date: 2009-05-10 4:45:26
Message-ID: 68002a310905092133o7bad9586o666df5b8fbbd08f2 () mail ! gmail ! com
[Download RAW message or body]
[Attachment #2 (multipart/alternative)]
Hi Gianluca,
Thanks for your information, That's great helpful. I decide to use a
hardware local timer to record the beacon frames arrival time. After I
looked close to the CACE AirPcap Classic wireless adapter, I found there are
a AIROHA transceiver and a ZYDAS USB driver chip. Do you know where does the
Winpcap implement the incoming packets filtering?
Cheers
John
2009/5/7 Gianluca Varenni <gianluca.varenni@cacetech.com>
>
>
> ----- Original Message -----
> *From:* John Wang <locationdev@gmail.com>
> *To:* winpcap-users@winpcap.org
> *Sent:* Wednesday, May 06, 2009 6:36 AM
> *Subject:* Re: [Winpcap-users] Where does the Winpcap
> timestampcomefrom?andothers
>
> Hi,
>
> I'm a little bit confused about where exactly the arrival packets
> timestamps come from, in our first email, you said:
>
> "1. Where does the NPF get the time information to timestamp these incoming
> packet? The time information comes from a on board timer in the adapter or
> from a CPU or similar computer clock?
> --GV--
> From the computer clock when the packet gets delivered to WinPcap."
>
> I think that means the timestamps come from computer timer, like CPU timer.
> But in you last email, you said:
>
> "The only way to obtain that is to have some device that timestamps
> packets in hardware. And even in that case, most of the times the timestamps
> have microsecond precision (this is what we have with the AirPcap adapters
> in hardware)."
>
> That sounds like, the AirPcap adapter has a timer build in it, and the
> arrival packets timestamps come from this build in timer.
>
> So I want to get the confirmation from you, whether the arrival packets are
> timestamped by the computer timer or the AirPcap adapter build in timer.
>
> In the case of the AirPcap adapters, which are *custom* capture devices, we
> provide two timestamps: software based ones and hardware based ones. The
> hardware based ones are generated by the chipset itself and have microsecond
> precision.
>
> If you use WinPcap on a standard network adapter (doesn't matter if it's
> wireless or not), you just have software timestamps.
>
> Let me know if this makes any sense to you.
>
> Have a nice day
> GV
>
>
> Cheers
>
> John
>
> ------------------------------
>
> _______________________________________________
> Winpcap-users mailing list
> Winpcap-users@winpcap.org
> https://www.winpcap.org/mailman/listinfo/winpcap-users
>
>
> _______________________________________________
> Winpcap-users mailing list
> Winpcap-users@winpcap.org
> https://www.winpcap.org/mailman/listinfo/winpcap-users
>
>
[Attachment #5 (text/html)]
Hi Gianluca,<br><br>Thanks for your information, That's great helpful. I decide \
to use a hardware local timer to record the beacon frames arrival time. After I \
looked close to the CACE AirPcap Classic wireless adapter, I found there are a AIROHA \
transceiver and a ZYDAS USB driver chip. Do you know where does the Winpcap implement \
the incoming packets filtering?<br> <br>Cheers<br><br>John<br><br><div \
class="gmail_quote">2009/5/7 Gianluca Varenni <span dir="ltr"><<a \
href="mailto:gianluca.varenni@cacetech.com">gianluca.varenni@cacetech.com</a>></span><br><blockquote \
class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt \
0pt 0.8ex; padding-left: 1ex;">
<div bgcolor="#ffffff">
<div><font size="2"></font> </div>
<blockquote style="border-left: 2px solid rgb(0, 0, 0); padding-right: 0px; \
padding-left: 5px; margin-left: 5px; margin-right: 0px;"><div class="im"> <div \
style="font-family: arial; font-style: normal; font-variant: normal; font-weight: \
normal; font-size: 10pt; line-height: normal; font-size-adjust: none; font-stretch: \
normal;">----- Original Message ----- </div> <div style="background: rgb(228, 228, \
228) none repeat scroll 0% 0%; -moz-background-clip: -moz-initial; \
-moz-background-origin: -moz-initial; -moz-background-inline-policy: -moz-initial; \
font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; \
font-size: 10pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"> \
<b>From:</b> <a title="locationdev@gmail.com" href="mailto:locationdev@gmail.com" \
target="_blank">John Wang</a> </div>
<div style="font-family: arial; font-style: normal; font-variant: normal; \
font-weight: normal; font-size: 10pt; line-height: normal; font-size-adjust: none; \
font-stretch: normal;"><b>To:</b> <a title="winpcap-users@winpcap.org" \
href="mailto:winpcap-users@winpcap.org" target="_blank">winpcap-users@winpcap.org</a> \
</div>
</div><div class="im"><div style="font-family: arial; font-style: normal; \
font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; \
font-size-adjust: none; font-stretch: normal;"><b>Sent:</b> Wednesday, May 06, 2009 \
6:36 AM</div>
<div style="font-family: arial; font-style: normal; font-variant: normal; \
font-weight: normal; font-size: 10pt; line-height: normal; font-size-adjust: none; \
font-stretch: normal;"><b>Subject:</b> Re: [Winpcap-users] Where does the Winpcap \
timestampcomefrom?andothers</div> <div><font \
size="2"></font><br></div></div><div><div></div><div class="h5">Hi,<br><br>I'm a \
little bit confused about where exactly the arrival packets timestamps come from, \
in our first email, you said:<br><br><span style="color: rgb(51, 51, \
255);">"1. Where does the NPF get the time information to timestamp these \
incoming packet? The time information comes from a on board timer in the adapter or \
from a CPU or similar computer clock?</span>
<div style="color: rgb(51, 51, 255);"><font color="#000000" size="2"></font> </div>
<div style="color: rgb(51, 51, 255);"><font size="2">--GV--</font></div>
<div><font style="color: rgb(51, 51, 255);" size="2">From the computer clock when
the packet gets delivered to WinPcap.</font><span style="color: rgb(51, 51, \
255);">"</span><br><br><font color="#000000">I think that means the timestamps \
come from computer timer, like CPU timer. But in you last email, you \
said:<br><br><span style="color: rgb(51, 51, 255);">"</span></font><font \
style="color: rgb(51, 51, 255);"><font size="2">The only way to obtain that is to \
have some device that timestamps packets in hardware. And even in that case, most \
of the times the timestamps have microsecond precision (this is what we have with \
the AirPcap adapters in hardware).</font></font><font color="#000000"><span \
style="color: rgb(51, 51, 255);">"<br><br><span style="color: rgb(0, 0, \
0);">That sounds like, the AirPcap adapter has a timer build in it, and the arrival \
packets timestamps come from this build in timer.<br><br>So I want to get the \
confirmation from you, whether the arrival packets are timestamped by the computer \
timer or the AirPcap adapter build in \
timer.<br></span></span></font></div></div></div></blockquote> <div><font \
color="#000000"><span style="color: rgb(51, 51, 255);"><span style="color: rgb(0, 0, \
0);"><font size="2">In the case of the AirPcap adapters, which are *custom* capture \
devices, we provide two timestamps: software based ones and hardware based ones. The \
hardware based ones are generated by the chipset itself and have microsecond \
precision. </font></span></span></font></div>
<div><font color="#000000"><span style="color: rgb(51, 51, 255);"><span style="color: \
rgb(0, 0, 0);"></span></span></font> </div> <div><font color="#000000"><span \
style="color: rgb(51, 51, 255);"><span style="color: rgb(0, 0, \
0);"></span></span></font><font color="#000000"><span style="color: rgb(51, 51, \
255);"><span style="color: rgb(0, 0, 0);"><font size="2">If you use WinPcap on a \
standard network adapter (doesn't matter if it's wireless or not), you just \
have software timestamps.</font></span></span></font></div> <div><font \
color="#000000"><span style="color: rgb(51, 51, 255);"><span style="color: rgb(0, 0, \
0);"></span></span></font> </div> <div><font color="#000000"><span style="color: \
rgb(51, 51, 255);"><span style="color: rgb(0, 0, 0);"></span></span></font><font \
color="#000000" size="2"><span style="color: rgb(51, 51, 255);"><span style="color: \
rgb(0, 0, 0);">Let me know if this makes any sense to \
you.</span></span></font></div> <div><font color="#000000" size="2"><span \
style="color: rgb(51, 51, 255);"><span style="color: rgb(0, 0, \
0);"></span></span></font> </div> <div><font color="#000000" size="2"><span \
style="color: rgb(51, 51, 255);"><span style="color: rgb(0, 0, \
0);"></span></span></font><font color="#000000" size="2"><span style="color: rgb(51, \
51, 255);"><span style="color: rgb(0, 0, 0);">Have a nice \
day</span></span></font></div><div class="im"> <div><font color="#000000" \
size="2"><span style="color: rgb(51, 51, 255);"><span style="color: rgb(0, 0, \
0);"></span></span></font><font color="#000000"><span style="color: rgb(51, 51, \
255);"><span style="color: rgb(0, 0, 0);"><font \
size="2">GV</font></span></span></font></div> <font color="#000000"><span \
style="color: rgb(51, 51, 255);"><span style="color: rgb(0, 0, 0);"><font \
size="2"></font></span></span></font> <blockquote style="border-left: 2px solid \
rgb(0, 0, 0); padding-right: 0px; padding-left: 5px; margin-left: 5px; margin-right: \
0px;"><font color="#000000"><span style="color: rgb(51, 51, 255);"><span \
style="color: rgb(0, 0, 0);"> \
<div><br>Cheers<br><br>John<br></div></span></span></font> <p>
</p><hr>
<p></p>_______________________________________________<br>Winpcap-users
mailing
list<br><a href="mailto:Winpcap-users@winpcap.org" \
target="_blank">Winpcap-users@winpcap.org</a><br><a \
href="https://www.winpcap.org/mailman/listinfo/winpcap-users" \
target="_blank">https://www.winpcap.org/mailman/listinfo/winpcap-users</a><br> \
</blockquote></div></div> <br>_______________________________________________<br>
Winpcap-users mailing list<br>
<a href="mailto:Winpcap-users@winpcap.org">Winpcap-users@winpcap.org</a><br>
<a href="https://www.winpcap.org/mailman/listinfo/winpcap-users" \
target="_blank">https://www.winpcap.org/mailman/listinfo/winpcap-users</a><br> \
<br></blockquote></div><br>
_______________________________________________
Winpcap-users mailing list
Winpcap-users@winpcap.org
https://www.winpcap.org/mailman/listinfo/winpcap-users
[prev in list] [next in list] [prev in thread] [next in thread]
Configure |
About |
News |
Add a list |
Sponsored by KoreLogic