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Date: Thu, 7 Jan 2010 01:19:59 +0530
Message-ID: <53b627ea1001061149l102ce517y5b7c3797c70e6284@mail.gmail.com>
Subject: Re: Cygwin and raw sockets - Windows XP with SP2 , Vista and later
From: Karthik Balaguru <karthikbalaguru79 AT gmail DOT com>
To: cygwin AT cygwin DOT com
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On Wed, Jan 6, 2010 at 11:27 PM, Larry Hall (Cygwin) wrote:
> On 01/06/2010 12:21 PM, Karthik Balaguru wrote:
>>
>> On Wed, Jan 6, 2010 at 10:04 PM, Larry Hall (Cygwin)
>> <reply-to-list-only-lh at cygwin> =A0wrote:
>
> =A0 =A0^^^^^^^^^^^^^^^^^^^
> <http://cygwin.com/acronyms/#PCYMTNQREAIYR> =A0Don't feed the spammers.
>

Okay, Taken care !

>>> On 01/06/2010 09:51 AM, Karthik Balaguru wrote:
>>>>
>>>> I got the below info from
>>>> http://www.cygwin.com/cygwin-ug-net/highlights.html#ov-hi-sockets =A0-
>>>> 'Socket-related calls in Cygwin basically call the functions by the
>>>> same name in Winsock, Microsoft's implementation of Berkeley sockets,
>>>> but with lots of tweaks.'
>>>> But, It does not clearly convey whether cygwin uses Microsoft's
>>>> winsock . Does cygwin use winsock ?
>>>> If cygwin uses winsock, then i think the raw socket usage restrictions
>>>> applied for further releases from 'Windows XP with SP2' is applicable
>>>> for cygwin also.:-(
>>>
>>> Cygwin does not provide its own implementation for sockets. =A0It uses
>>> Winsock V2 so basic restrictions imposed by Winsock will constrain
>>> Cygwin as well.
>>>
>>
>> Larry, Thx for the clarification.
>>
>> But, I came across the below link that conveys that the network
>> support in Cygwin is supposed to provide the POSIX API, not the
>> Winsock API -
>> http://www.cygwin.com/faq/faq.api.html#faq.api.net-functions
>> What does the above link refer to ?
>
> Right. It's a layer over Winsock that provides an API such that programs
> using the POSIX API will build. =A0That's largely syntax compatibility. =
=A0The
> semantics are also there for the most part but are limited by Winsock.
>
>> Interestingly ,the below link conveys that raw sockets is supported
>> unofficially ! Strange !
>> http://sourceware.org/ml/cygwin/2005-10/msg00753.html
>> But, how& =A0why is it supported unofficially ?
>
> It uses Winsock and is limited by it.

Okay !

>> The below link seems to convey the problems of using the Raw sockets
>> with Winsock and it also about the restrictions w.r.t various windows
>> releases =A0-
>> http://tangentsoft.net/wskfaq/advanced.html#rawsocket
>> So, is the method of usage of winpcap is the only way to use raw
>> sockets in cygwin environment ?
>>
>> =A0From http://www.winpcap.org/docs/docs_41b5/html/main.html , I find
>> that the purpose of WinPcap is to give this kind of access to Win32
>> applications that it provides facilities to:
>> 1. transmit raw packets 2. capture raw packets and 3. filter the packets
>> Any other ideas/ways apart from winpcap to use raw sockets in cygwin
>> environment ?
>
> Winpcap isn't a Cygwin package so this would be a Windows native approach.
> If you're developing a purely Windows app, then this would be a better way
> to go.
>

Okay, Thx for the clarification.

I got the below link that conveys the problems with winpcap usage with cygw=
in
http://www.mail-archive.com/winpcap-users AT winpcap DOT polito DOT it/msg02534.html
It seems to convey that winpcap can also easily be used with gcc using
the MinGW compile environment (www.mingw.org).
It also conveys that winpcap cannot be used from within a cygwin
environment as it depends on the MSVCRT.dll which, innately conflicts
with the cygwin1.dll

So, it can be put as below in brief -
1.For raw socket usage in a purely windows based application, winpcap
is the right choice.
WinPcap is an open source library for packet capture and network
analysis for the Win32 platforms.

2.For raw socket usage in a linux based application on cygwin
environment, libpcap would be the right choice

Thx,
Karthik Balaguru

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