IntroductionPacket capturing (or packet sniffing) is the process of collecting all packets of data that pass through a given network interface. Capturing network packets in our applications is a powerful capability which lets us write network monitoring, packet analyzers and security tools. The libpcap library for UNIX based systems and WinPcap for Windows are the most widely used packet capture drivers that provide API for low-level network monitoring. Among the applications that use libpcap/WinPcap as its packet capture subsystem are the famous tcpdump and Wireshark. In this article, we will introduce the SharpPcap .NET assembly (library) for interfacing with libpcap or winpcap from your .NET application and will give you a detailed programming tutorial on how to use it.Background Tamir Gal started the SharpPcap project around 2004. He wanted to use WinPcap in a .NET application while working on his final project for university. The project involved analyzing and decoding VoIP traffic and he wanted to keep coding simple with C# which has time saving features like garbage collection. Accessing the WinPcap API from .NET seemed to be quite a popular requirement, and he found some useful projects on CodeProject's website that let you do just that: Packet Capture and Analyzer
Raw Socket Capturing Using C#
Packet sniffing with winpcap functions ported to a .NET library
The first project is a great ethereal .NET clone that lets you capture and analyze numerous types of protocol packets. However, a few issues with this project make it almost impossible to be shared among other .NET applications. Firstly, the author did not provide any generic API for capturing packets that can be used by other .NET applications. He didn't separate his UI code and his analyzing and capturing code, making his capturing code depend on the GUI classes such as ListView to operate. Secondly, for some reason the author chose to re-implement some of WinPcap's functions in C# by himself rather than just wrapping them. This means that his application can't take advantage of the new WinPcap versions since he hard coded a certain version of WinPcap in his application. The second and the third articles are nice starts for wrapper projects for WinPcap, however they didn't provide some important WinPcap features such as handling offline pcap files and applying kernel-level packet filters, and most importantly they provide no parser classes for analyzing protocol packets. Both projects didn't post their library source code together with the article in order to let other people extend their work and add new features and new packet parser classes. And so, Tamir decided to start his own library for the task. Several versions in the 1.x series were released. Development slowed towards mid-2007 when the last version in the 1.x series was released, SharpPcap 1.6.2. Chris Morgan took over development of SharpPcap in November of 2008. Since then SharpPcap has had major internal rewrites and API improvements.In late February 2010, SharpPcap v3.0 was released. This release represents a rewrite of SharpPcap's packet parsers. Packet parsing functionality was broken out into a new library, Packet.Net. SharpPcap takes care of interfacing with libpcap/winpcap and Packet.Net takes care of packet dissection and creation. The details of Packet.Net's architecture will be discussed later in the tutorial. SharpPcap v3.5 was released February 1st, 2011. The 3.5 release contains significant API changes as well as WinPcap remote capture and AirPcap support.About SharpPcapThe purpose of SharpPcap is to provide a framework for capturing, injecting and analyzing network packets for .NET applications. SharpPcap is openly and actively developed with its source code and file releases hosted on SourceForge. Source code patches to improve or fix issues are welcome via the sharppcap developers mailing list. Bug reports, feature requests and other queries are actively answered on the support forums and issue trackers there so if you have any trouble with the library please feel free to ask. SharpPcap is a fully managed cross platform library. The same assembly runs under Microsoft .NET as well as Mono on both 32 and 64bit platforms.Read more: Codeproject
Raw Socket Capturing Using C#
Packet sniffing with winpcap functions ported to a .NET library
The first project is a great ethereal .NET clone that lets you capture and analyze numerous types of protocol packets. However, a few issues with this project make it almost impossible to be shared among other .NET applications. Firstly, the author did not provide any generic API for capturing packets that can be used by other .NET applications. He didn't separate his UI code and his analyzing and capturing code, making his capturing code depend on the GUI classes such as ListView to operate. Secondly, for some reason the author chose to re-implement some of WinPcap's functions in C# by himself rather than just wrapping them. This means that his application can't take advantage of the new WinPcap versions since he hard coded a certain version of WinPcap in his application. The second and the third articles are nice starts for wrapper projects for WinPcap, however they didn't provide some important WinPcap features such as handling offline pcap files and applying kernel-level packet filters, and most importantly they provide no parser classes for analyzing protocol packets. Both projects didn't post their library source code together with the article in order to let other people extend their work and add new features and new packet parser classes. And so, Tamir decided to start his own library for the task. Several versions in the 1.x series were released. Development slowed towards mid-2007 when the last version in the 1.x series was released, SharpPcap 1.6.2. Chris Morgan took over development of SharpPcap in November of 2008. Since then SharpPcap has had major internal rewrites and API improvements.In late February 2010, SharpPcap v3.0 was released. This release represents a rewrite of SharpPcap's packet parsers. Packet parsing functionality was broken out into a new library, Packet.Net. SharpPcap takes care of interfacing with libpcap/winpcap and Packet.Net takes care of packet dissection and creation. The details of Packet.Net's architecture will be discussed later in the tutorial. SharpPcap v3.5 was released February 1st, 2011. The 3.5 release contains significant API changes as well as WinPcap remote capture and AirPcap support.About SharpPcapThe purpose of SharpPcap is to provide a framework for capturing, injecting and analyzing network packets for .NET applications. SharpPcap is openly and actively developed with its source code and file releases hosted on SourceForge. Source code patches to improve or fix issues are welcome via the sharppcap developers mailing list. Bug reports, feature requests and other queries are actively answered on the support forums and issue trackers there so if you have any trouble with the library please feel free to ask. SharpPcap is a fully managed cross platform library. The same assembly runs under Microsoft .NET as well as Mono on both 32 and 64bit platforms.Read more: Codeproject
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