Проброс портов IPtables CentOS7 / Port Forwarding IPtables CentOS7

sysctl -w net.ipv4.ip_forward=1

vi /etc/sysctl.conf
net.ipv4.ip_forward = 1

sysctl -p /etc/sysctl.conf

iptables -t nat -A PREROUTING -p tcp --dport 25 -j DNAT  --to 192.168.1.243:25

iptables -A FORWARD -p tcp --dport 80 -d 192.168.1.243 -j ACCEPT