Why is iptables not broadcasting the real IP?

Question

iptables

Installed gateway on iptables. I forward port 10003 from external interfaces to local IP. All packets come from the local ip gateway, and external ones are not visible. Google shows the same configs as mine. Tell me how to broadcast the external ip of the client when forwarding the port?

*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]

-A INPUT -i eth1 -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -p gre -j ACCEPT
-A INPUT -p tcp -m multiport --ports 22 -j ACCEPT
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p icmp -m icmp --icmp-type 3 -j ACCEPT
-A INPUT -p icmp -m icmp --icmp-type 11 -j ACCEPT
-A INPUT -p icmp -m icmp --icmp-type 12 -j ACCEPT
-A INPUT -p icmp -m icmp --icmp-type 8 -j ACCEPT

-A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT

COMMIT

*nat
:PREROUTING ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]

-A PREROUTING -p tcp -m tcp --dport 10003 -j DNAT --to-destination 192.168.100.237:10003

-A POSTROUTING -j MASQUERADE
-A POSTROUTING -o eth0 -j MASQUERADE
-A POSTROUTING -o eth1 -j MASQUERADE

COMMIT

*mangle
:PREROUTING ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
COMMIT

Answer 1

-A POSTROUTING -j MASQUERADE

this is ruining everything