How to pass two routers

[Gordon Messmer]

There's no need to use NAT, proxy servers, or oddball iptables rules to 
accomplish what roland described.

As Dario pointed out, you have two options:

1) Set up a static route on each server in LAN A so that they use 
192.168.0.99 as their default gateway and 192.168.0.98 as the gateway 
for the network in LAN B.  You can configure the route using Fedora's 
network configuration tools.

2) Set up a static route on the router at 192.168.0.99 using 
192.168.0.98 as the gateway for the network in LAN B.  This will 
simplify the configuration of all of the servers in LAN A, since they 
don't need a route of their own.