Conventions used

There are a number of text conventions used throughout this book.

Code in text: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "Go ahead and open the PCAP file labeled 4SICS-GeekLounge-151021.pcap with Wireshark."

A block of code is set as follows:

def run_async_server(): 
    store = ModbusSlaveContext( 
        di=ModbusSequentialDataBlock(0, [17]*100), 
        co=ModbusSequentialDataBlock(0, [17]*100), 
        hr=ModbusSequentialDataBlock(0, [17]*100),

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

import logging 
FORMAT = ('%(asctime)-15s %(threadName)-15s'  
          '%(levelname)-8s %(module)-15s:%(lineno)-8s %(message)s') 
logging.basicConfig(format=FORMAT) 
log = logging.getLogger() 
log.setLevel(logging.DEBUG)

Any command-line input or output is written as follows:

tcpdump -i <interface> -v -X

Bold: Indicates a new term, an important word, or words that you see onscreen. For instance, words in menus or dialog boxes appear in bold. Here is an example: "We will want to set the port mirroring, so select the Monitoring option from the menu on the left and then select Port Mirror."

Tips or important notes

Appear like this.