Can't reach static IP address from inside LAN

We use an SMC modem/router and have a LAN of several computers connected to it, using the SMC's DHCP server and NAT. We also have a CentOS server ("ngmfs3") with two network interfaces: eth0 uses a static IP address provided by Comcast, while eth2 uses a static IP address on the LAN subnet.

I can ping ngmfs3 eth0 from a box outside the building, and I can reach the Internet from ngmfs3, with whatismyip.com showing the correct static IP address.

I can ping ngmfs3 eth2 from a computer inside the LAN.

However, I can't reach the public static IP address from inside the LAN.

On the SMC modem under Firewall Options, I have "Disable Firewall for True Static IP Subnet Only" and "Disable Gateway Smart Pcket Detection" both checked. Under Port Configuration -> True Static IP Port Management, I have "Disable all rules and allow all inbound traffic through" checked.

Any idea why the modem isn't directing packets from inside the LAN subnet to the static IP address correctly?

Responses

Accepted Solution

tsummers

Frequent Contributor

•

39 Messages

11 years ago

The SMC does not support IP reflection. You will not be able to access the public static IP from within the LAN. You might want to consider split DNS, or a host file to direct the request to the internal IP address for whatever service you are trying to reach.

0

Accepted Solution

lwitzel

New problem solver

•

2 Messages

11 years ago

Thanks, tsummers. The odd thing is, the CentOS box replaces an Xserve that worked. We were able to reach the static IP address from inside the LAN.

We solved it by changing the PHP code that was referring users to that domain, directing them instead to the internal IP address if they are coming from inside our LAN. For us, that was easier than setting up a split DNS.

0

Accepted Solution

Comcast_Jon

Administrator

•

1.5K Messages

11 years ago

Hello Iwitzel,

Thank you for sharing this information and update with the community.

We appreciate it and look forward to your future contribution.

Thank you

0