$ ls -l /sys/class/net/*/device/driver
lrwxrwxrwx 1 root root 0 Oct 11 14:03 /sys/class/net/eth1/device/driver -> ../../../../bus/pci/drivers/skge
lrwxrwxrwx 1 root root 0 Oct 11 14:03 /sys/class/net/eth3/device/driver -> ../../../../bus/pci/drivers/8139too

Thanks to bldewolf. / Gracias a bldewolf.