NIC 1 is used for internal network connection.
NIC 2 is used for Broad band internet connection which has static IP.
Now in this server my sendmail on 25 , POP3 on 110, HTTPD on 90 Is running now I want to allow user to access this services from outside my network or on internet.
In this box I have my firewall and for that I have to reconfigure and opened port 25, 110, 90 so outside user can access it.
After opening port and checking my settings I am only able to access POP3 service.
Because my sendmail & HTTPD is configure on my local/internal IP.
So which ever request comes inside for port 25 and port 90 I need to forward to my local/internal ip port 25 and 90.
So need to add below in my rc.local file for route the request.
Iptables –t nat –A PREROUTING –i eth1 –p tcp – -dport 25 –j DNAT - -to
Iptables –t nat –A PREROUTING –i eth1 –p tcp – -dport 90 –j DNAT - -to
After doing routing I am able to access.