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I have the following scenario which is giving me fits. I have a block of IP addresses on a .248 subnet. The service is Comcast, and the modem uses IP addres ending in .246. On the router for my private NAT, I use .241 as my router's IP address and .246 as it's gateway. The NAT is working fine, EXCEPT, which I try to connect to any of the machines between .241 and .246. From outside my NAT, all of the public IPs are working fine.

How do I configure my router to correctly route from the NAT to my public IP addresses that are on the .248 subnet?

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  • The router is a Netgear WNR200v4. I have a 192.16.1.0 NAT behind the router. In front of the router is the .248 subnet, including an IP in that subnet for the router.
    – Payton Byrd
    Dec 19, 2013 at 18:56
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    Is this for a home network or office network? If this is a home network why do you have machines sitting between your router and your public facing IP? From your question, your network layout sounds something like this Comcast (DHCP down)->(.246 ip) Modem (static IP's down)->(.241)WiFi router (NAT)->internal network .. is that about right? You might want to put a small diagram of some sort (even textual) to represent HOW you're network is setup and maybe why (i.e. do you have some outward facing services you need outside your NAT/DMZ?), that could help diagnose.
    – txtechhelp
    Dec 19, 2013 at 21:10

1 Answer 1

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I have a block of IP addresses on a .248 subnet.

This is confusing. "Subnet" has to do with the part of the IP address from the beginning (left), not end, i.e. 192.168.2.1/24 (equivalent 192.168.2.1 with netmask 255.255.255.0) is in the 192.168.2.0 subnet.

Sounds like you have a /29 subnet. Meaning your netmask is 255.255.255.248.

Check to make sure on your NAT router that the subnet mask is set correctly. If you left the subnet mask to what is likely the default, 255.255.255.0, it may be thinking some addresses are private when they are actually public.

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