Network Security Tools

Sending the Packet

Once we have assembled our protocol blocks, in order from highest-level protocol to lowest-level protocol, we can write this packet to the network. We do this using libnet_write( ), as shown in Example 11-5.

Example 11-5. Writing the packet

/* write the packet */
if ((libnet_write (l)) == -1)
  {
    fprintf (stderr, "Unable to send packet: %s\n", libnet_geterror (l));
    exit (1);
  }

The libnet_write( ) function causes libnet to assemble the packet from the protocol blocks. Then this is sent on the network, either to the IP address supplied for an injection at the LIBNET_RAW level, or to the network hardware address if the injection is at the LIBNET_LINK layer.