linux - Iptables NAT (PAT) A to B to C and back

I want to access via SSH a DB server from an outside network via a linux (CentOS) gateway with two interfaces in separate networks as it follow below:

Admin PC IP: 10.21.1.8

Linux GW IP eth1 Outside: 10.21.1.199 - SSH Port 10051

Linux GW IP eth2 Inside: 10.10.4.151

DB Server IP: 10.10.4.51 - SSH Port 22

FLOW: 10.21.1.8 --> eth1:10.21.1.199:10051 --> eth2:10.10.4.151 --> 10.10.4.51:22

and the return path

10.10.4.51 --> eth2:10.10.4.151 --> 10.21.1.199 --> 10.21.1.8

The iptables rules that i tried seems to be wrong..
Something similar with :

iptables -t mangle -A PREROUTING -d  -p tcp --dport 2223 -j MARK --set-mark 1 -i eth0

iptables -t nat -A PREROUTING -p tcp -m mark --mark 1 -j DNAT --to-destination :2222 -i eth0

iptables -t nat -A POSTROUTING -m mark  --mark 1 -j SNAT --to-source  -o eth1 

iptables -A FORWARD -m mark --mark 1 -j ACCEPT -o eth1

Need some hint..thx..