Since just doing a cronjob every morning, before the router reboots:
ifconfig > "`date`.ifconfig.txt"
isn't very effective, since after ~4 GByte's the counter in the ifconfig will go to zero. So if there was ~5 GByte traffic, only 1 GByte will be in the txt file.
My question: How can I measure daily traffic with OpenWRT 12.04?