Hello Mark,
You have 2 options...
For single ampr IP setups, you can use a 1 rule solution:
ip route add default via 169.228.66.251 dev ampr0 onlink table default ip rule add from 44.182.21.1 table default
substitute the interface name in the route command and your ampr address in the rule sets. This assumes that the ampr routes are in the table 'main'. If not substitute with your table name. Of course you can use another table instead of default. But this table is already there and usually empty.
If you need to forward IP ranges, the easiest way is to use routing marks and a table, again substitute with your values. You can use any numeric value to mark the route...
ip route add default via 169.228.66.251 dev ampr0 onlink table default ip rule add fwmark 44 table default iptable -t mangle -A PREROUTING -i ampr0 -p all ! -s 44.0.0.0/8 -d 44.182.20.0/24 -j MARK --set-mark 44 iptable -t mangle -A PREROUTING ! -i ampr0 -p all -s 44.182.20.0/24 ! -d 44.0.0.0/8 -j MARK --set-mark 44 iptable -t mangle -A OUTPUT -p all -s 44.182.20.0/24 ! -d 44.0.0.0/8 -j MARK --set-mark 44
This will mark all traffic from non-ampr addresses via tunnel and all outgoing and forwarded ampr traffic to non-ampr hosts with routing mark 44 and use table default to forward the replies it to the default gw 169.228.66.251 via tunnel.
Have fun,
Marius, YO2LOJ