Well, using tools such as DBAN or the like is not only pointless, it is also very time consuming. You do NOT need to do anything else but fill the drive with 0x00 (zero bytes / NUL) once and only once, in order to prevent the recovery of any former data. Doing multiple passes is excessive and useless, let alone filling the drive with random data. The only way you can try to somehow restore anything, after such an operation took place, is with an atomic microscope - this is, obviously, an extreme procedure, that will take months for even the smallest JPG file and the error rate (false-positives) is going to be immense (in other words - you won't get anything meaningful out of this). This is even more true for higher capacity models (higher density platters).
So, the ultimate software way (fast, reliable & very secure), is a single run (zero-fill) of dd:
dd if=/dev/zero of=/dev/sdX bs=1M
However, there is something called secure erase. This is an established ATA standard. This function is integrated into the drive itself. Not only is it even faster than a run of dd (as it's already hardware based and hardware > software, speed wise), it is also more secure, due to the ability of purging original bad sectors that have been reallocated! There are 2 versions: the vanilla (2001 and onwards) and the enhanced one (post 2004). So, if your drive was manufactured roughly 10 years ago - it already supports this feature.
hdparm --security-erase NULL /dev/sdX
hdparm --security-erase-enhanced NULL /dev/sdX