IP redirect wasn't actually what you were wanting to do in the strict sense of the definition. An IP redirect is where a router tells a device that it knows a better route to the destination via a different router. In other words, "don't send your data to me, I can tell you a better way of getting it to the far end".
RFC 777 says:-
Description
The gateway sends a redirect message to a host in the following
situation. A gateway, G1, receives an internet datagram from a
host on a network to which the gateway is attached. The gateway,
G1, checks its routing table and obtains the address of the next
gateway, G2, on the route to the datagram's internet destination
network, X. If G2 and the host identified by the internet source
address of the datagram are on the same network, a redirect
message is sent to the host. The redirect message advises the
host to send its traffic for network X directly to gateway G2 as
this is a shorter path to the destination. The gateway forwards
the original datagram's data to its internet destination.
Pete
