I have a Linux-Board with two Ethernet-Interfaces (eth0, eth1). On eth0 I have a IPv4 network, on eth1 there's a IPv6 network. Now I want to route packets from specific devices on the IPv4-network to the IPv6-network and vice versa. Each IPv4-device has a unique IPv6-address and each IPv6-device has a unique IPv4-adress which shall be specified in a textfile. I read about tayga but it seems that I can use it with only one eth-interface. I don't know if this is really what I need. Isn't it possible to manage this with standard linux tools? Do you think a simple C-program which receives IP-Packages on one interface, changes the IP-addresses and IP-PDU-Layout, and sends it back on the other interface will work?
If I understand your situation correctly I think the best solution for you would be to use SIIT-DC (SIIT-DC: Stateless IP/ICMP Translation for IPv6 Data Center Environments). It allows you to map an IPv4 address to an IPv6 address and vice versa.
The tool to do this with I personally like best is Jool. It is a Linux kernel module that implements both NAT64 and SIIT.