Check out vnStat. I can't post the URL because I have not posted 5 times to the Forum. I have used it on Linux and FreeBSD and it works with no issues.
Here's the output
Code:
rbelk@rbvmwk:~$ vnstat --help
vnStat 1.9 by Teemu Toivola <tst at iki dot fi>
-q, --query query database
-h, --hours show hours
-d, --days show days
-m, --months show months
-w, --weeks show weeks
-t, --top10 show top10
-s, --short use short output
-u, --update update database
-i, --iface select interface (default: eth0)
-?, --help short help
-v, --version show version
-tr, --traffic calculate traffic
-ru, --rateunit swap configured rate unit
-l, --live show transfer rate in real time
rbelk@rbvmwk:~$ vnstat
Database updated: Mon Nov 30 11:55:02 2009
em0 since 10/04/09
rx: 32.37 GiB tx: 84.11 GiB total: 116.49 GiB
monthly
rx | tx | total | avg. rate
------------------------+-------------+-------------+---------------
Oct '09 17.21 GiB | 34.81 GiB | 52.02 GiB | 162.92 kbit/s
Nov '09 15.17 GiB | 49.30 GiB | 64.47 GiB | 211.91 kbit/s
------------------------+-------------+-------------+---------------
estimated 15.40 GiB | 50.07 GiB | 65.48 GiB |
daily
rx | tx | total | avg. rate
------------------------+-------------+-------------+---------------
yesterday 128.09 MiB | 1.25 GiB | 1.38 GiB | 133.91 kbit/s
today 69.58 MiB | 404.34 MiB | 473.91 MiB | 90.49 kbit/s
------------------------+-------------+-------------+---------------
estimated 138 MiB | 813 MiB | 951 MiB |