A minimum cpp wrapper for pcap for live Rx and Tx

This is a minimum pcap wrapper that creates a live Tx or Rx object for a network interface. For a more comprehensive tool check out PcapPlusPlus.

Dependecies

1. libpcap

Create an interface (linux) [optional]

For some applications, an interface may be created prior to creating Chipset::Rx or Chipset::Tx instances, then the name of that interface shall be passed to Chipset::Rx / Chipset::Tx constructors.

Here is an example of creating a new interface on a wifi card on a linux machine with iw tool:

>> iw PHY_NAME interface add INTERFACE_NAME type monitor flags fcsfail control
>> ifconfig INTERFACE_NAME up

• PHY_NAME is usually something like phy2 (you can type iw to get a list of avaiable phys and declared interfaces on each phy).

• INTERFACE_NAME is arbitrary and is the name that should be passed to Chipset::Rx / Chipset::Tx constructors.

• In many cases the interface needs to be in monitor mode to allow arbitrary Tx or receive frames that are not addressed to the device.

• fscfail and and control flags are optional, you can learn more about the flags in iw manual.

• In some cases depending on the wifi card, other interfaces on the same card should be down. To shut down and interface (wlan1) for example:

  >> ifconfig wlan1 down

Sample code

#include <unistd.h>
#include "chipset_rx.h"
#include "chipset_tx.h"

// all debug messages are printed to std::cout
bool verbose = true;
// Warnings are always printed to std::cout, errors to std::cerr. See out.h.

void rx_callback(uint64_t timeStamp, std::string packet){
    /* take care of the incoming packet */
    std::cout << timeStamp;
}

int main(int argc, char **argv)
{
    Chipset::Rx rx("rxInterfaceName", rx_callback);

    // Set filter (optional)
    std::string filter ("ether host 00:de:ad:be:ef:00");
    rx.setFilter(filter);

    // Open interface for capturing
    rx.open();

    // Run for 10 seconds
    usleep(10000);
    
    // Stop capture
    rx.stop();
    
    return 0;
}

Related

• tshark
• PcapPlusPlus.
• tcpdump