Friends,

The networking setup in my office is as follows.

One Ubuntu machine with 2 NIC is made as a gateway

eth1 : The Public interface which is connected to the modem
The IP no 192.168.1.1 is assigned(dhcp) in eth1 interface

We have static IP address provided by the ISP (117.218.X.X)


eth0 : The Local interfaces connecting to internal
(static IP assigend as 192.168.0.78)
machines(192.168.0.x/255.255.255.0)

Now, a web application has been developed in LAMP and hosted in the machine 192.168.0.48 and is available to around 50 computers in our office.

We would like to this machine 192.168.0.48 as a public server so that the sub offices (around 200 nos) can access the application. I think port forwarding the procedure and adding the following rules to the iptables will work ( Am I correct?)

#iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 80 -j DNAT --to 192.168.0.48:80

#iptables -A FORWARD -p tcp -d 192.168.0.48 -j ACCEPT

This is the iptables rules of the gateway

===============================================

:PREROUTING ACCEPT [19:1629]

:INPUT ACCEPT [8:693]

:OUTPUT ACCEPT [3:178]

:POSTROUTING ACCEPT [1:73]

-A POSTROUTING -o eth0 -j MASQUERADE

COMMIT

# Completed on Thu Jul 30 12:24:51 2015

# Generated by iptables-save v1.4.21 on Thu Jul 30 12:24:51 2015

*filter

:INPUT ACCEPT [22:1237]

:FORWARD ACCEPT [5:420]

:OUTPUT ACCEPT [18:762]

-A FORWARD -i eth1 -j ACCEPT

COMMIT
=============================================================


If I am wrong, correct and guide me [It is urgent pls]

Did you check the value of /proc/sys/net/ipv4/ip_forward? Should be one by the way

It is 1

Now I have forwarded the port ( 80 ) in the router ( the ISP modem) and the machine is accessible to the public by using the static IP.

The modem is having network interfaces
1) Static IP 117.x.x.x as the incoming network from ISP
2) IP Nos 192.168.1.1 as the internal interface ( dhcp )

The Linux gateway has the following NICS

1) 192.168.1.2 from the modem.
2) 192.168.0.1 (Rules were already there as mentioned in the first post)

Now the web server is accessible from the internal machine 192.168.1.2, but I want to use a machine in 192.168.0.x as the web server using the IP tables rules of the gateway Ubuntu Machine.