So, here is my way to keep track of bandwidth usage using vnstat in Ubuntu.

Q. What is vnstat?
A. vnStat is a console-based network traffic monitor for Linux and BSD that keeps a log of network traffic for the selected
    interface(s).

Simply install the vnstat from Ubuntu repository with you favorite installation method ( synaptic / aptitude / apt-get / …). I am apt-get fan.

person@CANONICALDESK:~$ sudo apt-get install vnstat

Now, as i said i want to keep track of bandwidth usage of my Reliance Netconnect Broadband+ service. Which is always running to ‘ppp0′ interface. So first create the database of ‘ppp0′ for vnstat.

person@CANONICALDESK:~$ sudo vnstat -u -i ppp0

Error:

Unable to read database "/var/lib/vnstat/ppp0".

-> A new database has been created.

person@CANONICALDESK:~$

You can also discover more option using “vnstat -h”. Now every five minutes vnstat will run through cron to track the detail usage of bandwidth (TX + RX @ ppp0). I am not sure when i am going to shutdown / hibernate / sleep my machine. Still i want as much accurate result as i can. Because of that i have decreased the default 5 minutes schedule time to 1 minute for vnstat. Here is my modified vnstat cron script.

person@CANONICALDESK:~$ cat /etc/cron.d/vnstat

# /etc/cron.d/vnstat: crontab entries for the vnstat package

* *	* * *	root	if [ -x /usr/bin/vnstat ] && [ `ls /var/lib/vnstat/ | wc -l` -ge 1 ]; then /usr/bin/vnstat -u; fi

person@CANONICALDESK:~$

Time to take reports. We can also check / compare bandwidth usage with Reliance Mycare on-line report, which never generated for me

Monthly Rport:

person@CANONICALDESK:~$ vnstat -i ppp0 -m

 ppp0  /  monthly

   month         rx      |      tx      |   total
-------------------------+--------------+--------------------------------------
  Jul '09       1.00 GB  |    63.47 MB  |     1.06 GB   %%%%%%%%%%%%%%%%%%%%%:
-------------------------+--------------+--------------------------------------
 estimated      2.69 GB  |      169 MB  |     2.85 GB
person@CANONICALDESK:~$

Weekly Report:

person@CANONICALDESK:~$ vnstat -i ppp0 -w

	ppp0  /  weekly

	                    rx      |       tx      |    total
	----------------------------+---------------+--------------
	  last 7 days    418.01 MB  |     39.00 MB  |    457.01 MB
	    last week    606.37 MB  |     24.46 MB  |    630.83 MB
	 current week    418.01 MB  |     39.00 MB  |    457.01 MB
	----------------------------+---------------+--------------
	    estimated       447 MB  |        41 MB  |       488 MB
person@CANONICALDESK:~$

Daily Report:

person@CANONICALDESK:~$ vnstat -i ppp0 -d

 ppp0  /  daily

    day         rx      |     tx      |  total
------------------------+-------------+----------------------------------------
   03.07.    251.93 MB  |   11.99 MB  |  263.92 MB   %%%%%%%%%%%%%%%%:
   04.07.    354.43 MB  |   12.48 MB  |  366.91 MB   %%%%%%%%%%%%%%%%%%%%%%%%:
   09.07.    140.25 MB  |   19.11 MB  |  159.36 MB   %%%%%%%%%:
   10.07.     60.12 MB  |   10.25 MB  |   70.37 MB   %%%:
   11.07.    148.81 MB  |    6.27 MB  |  155.08 MB   %%%%%%%%%%
   12.07.     68.83 MB  |    3.39 MB  |   72.22 MB   %%%%
------------------------+-------------+----------------------------------------
 estimated      124 MB  |       5 MB  |     129 MB
person@CANONICALDESK:~$

Hourly Report:

person@CANONICALDESK:~$ vnstat -i ppp0 -h
 ppp0                                                                     13:09
  ^                                                                    r
  |                                                                    r
  |                                                                    r
  |                                                                    r
  |                                                                    r
  |                                                                    r
  |                                                                    r
  |                                                                    r
  |                                                                    r
  |                                                                    r
 -+--------------------------------------------------------------------------->
  |  14 15 16 17 18 19 20 21 22 23 00 01 02 03 04 05 06 07 08 09 10 11 12 13    

 h   rx (kB)    tx (kB)      h   rx (kB)    tx (kB)      h   rx (kB)    tx (kB)
14          0          0    22          0          0    06          0          0
15          0          0    23          0          0    07          0          0
16          0          0    00          0          0    08          0          0
17          0          0    01          0          0    09          0          0
18          0          0    02          0          0    10          0          0
19          0          0    03          0          0    11          0          0
20          0          0    04          0          0    12      70595       3506
21          0          0    05          0          0    13        311        108
person@CANONICALDESK:~$

I think above reports are sufficient to make argument against unfair bill right . There is also web base support for this application. Please do “Google” for more information.

Update:

If you want to stick with latest version of vnstat. Then please follow this