I have a file which contains raw IP packets in binary form.  The data in the file contains a full IP header, TCP\UDP header, and data.  I would like to use any language (preferably python) to read this file and dump the data onto the line.
In Linux I know you can write to some devices directly (echo "DATA" > /dev/device_handle).  Would using python to do an open on /dev/eth1 achieve the same effect (i.e. could I do echo "DATA" > /dev/eth1)
No; there is no /dev/eth1 device node -- network devices are in a different namespace from character/block devices like terminals and hard drives. You must create an AF_PACKET socket to send raw IP packets.
Writing raw IP data to an interface (linux)