Trabalhando com NAT

iptables -t nat -A PREROUTING -d 200.157.231.195 -p tcp --dport 5900 -j DNAT
--to-destination 192.168.0.253

iptables -t nat -A POSTROUTING -s 192.168.0.253 -p tcp --dport 5900 -j SNAT
--to-source 200.157.231.195

iptables -A FORWARD -d 192.168.0.253 -p tcp --dport 5900 -m state --state NEW,ESTABLISHED -j ACCEPT