Can't access internet through 2003 as router

Case Study - Can't access the Internet through Windows Server 2003 as a router

Situation: A law firm IT department supports three attorney offices. Recently, they decided to separated the LAN into three subnets by adding a Windows Server 2003 with four network cards as a router.

The Windows 2003 Standard Server was configured with RRAS and DHCP capabilities. The 4 NICs were installed and configured (192.168.0.1 connecting to a Sonicwall firewall, 192.168.1.0/24 for the LAN1, 192.168.2.0/24 for LAN2 and 192.168.3.0/24 for the LAN3). RRAS was installed using the custom configuration option with just LAN Routing. DHCP was installed and configured.

Problem: The router server can ping all LAN and access the Internet. But no computers in three LANs can access the Internet. They can ping the inside IP of the server but not the outside NIC's IP, 192.168.0.1. So, they called ChicagoTech.net for help.

Troubleshooting:

1. Ipconfig /all on the server displayed correct settings and IP routing was enabled.

2. Re-configured the RRAS.

3. No ISA, NAT or oother security software running.

4. No filtering blocked the traffic.

5. Client ipconfig /all displayed uncorrected default gateway which was assigned by DHCP, for example, a computer in the LAN1 had default IP 192.168.0.1 instead of 192.168.1.1. Note: default gateway must in the same subnet.

Resolution: modified the DHCP Scope Options and assigned the router accordingly.

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