What protocols are supported over IP by the Linux ip forwarding?

I need to route particular OSI protocols (CLNP and IDRP) over IP on a Linux router. My router works fine for TCP but it does not seem to work for these required protocols.

I looked at net/ipv4/ip_forward.c in the Linux kernel and it appears that only TCP, UDP and ICMP were foreseen, but I am not sure if I am looking at the right file.

I suspect that I would need to set up a VPN to route my data.

I would appreciate any hints you could provide.