We can check the status of data transfer using vnstat command. Install it by the command
yum install vnstat
Main configuration files: /etc/vnstat.conf and /etc/sysconfig/vnstat
USAGE
vnstat vnstat -i interface vnstat -i interface -option
To see eth0 stats, enter : vnstat -i eth0
To see daily stats for eth0, enter : vnstat -i eth0 -d
To see hourly network stats, enter : vnstat -i eth0 -h
To see monthly network stats, enter : vnstat -i eth0 -m
To see weekly network stats, enter : vnstat -i eth0 -w