Using a public IP for select hosts in a LAN

Question

I have a small company and we just started out. Given our size, we really can't get a dedicated network guy for now. Recently, we moved to a lease line of our own for reliability. This is the information I was provided with (the addresses mentioned here are just examples, obviously):

IP Address WAN: 35.34.33.70
SUBNET MASK   : 255.255.255.252
GATEWAY       : 35.34.33.69

LAN POOL IP   : 35.34.33.88/ 29
START IP      : 35.34.33.90
END IP        : 35.34.33.94
BROADCAST IP  : 35.34.33.95
SUBNET MASK : 255.255.255.248
GATEWAY :106.51.238.89

I setup my router, to basically have a NAT, which assigns all devices that connect to the router to get a 192.168.1.X IP address. The router's IP is set to the IP Address WAN given above and the gateway/subnet mask that was provided for the WAN. Everything is fine, and all devices have internet connectivity and local networking is working just fine. This is how my setup looks like:

+-------------+     +--------+     +---------+
| Set-top box | --- | Router | --- | Devices |
+-------------+     +--------+     +---------+
                        |          +---------+
                        +--------- | Devices |
                                   +---------+

The set-top box has only 1 ethernet cable. I have a couple of questions:

• Are the 'LAN pool ips' publically accessible (it looks to me that they are).
• Can I give one of the devices connected to my router one of these public ips? One of the device uses 192.168.1.187 and we use it from external networks by setting up port-forwarding on the router.
• What is the exact distinction between the LAN POOL and the WAN. I am not sure I entirely understand this distinction. The last part of the IP in WAN is '70', in gateway is '69', and in the pool, the IPs are from 90-94 with 95 as broadcast. The remaining part is exactly the same for all the IP addresses. What is the significance of this?

Sorry about the long post, and thank you for helping me out!

Answer 1

Answers to your questions:

1. Yes, they are public IPs

2. Yes, you create a static translation between 192.168.1.187 and one of your pool addresses. The details depend on the specific hardware you have.

3. The IP address WAN and gateway are the network that connects you to your provider. The WAN pool is a network of IP addresses that you can use for your devices. They are two separate networks. Although it usually doesn't matter, you would normally translate your internal addresses to one of the WAN pool addresses.

Answer 2

I would assume that the "IP Address WAN" is the IP that should be used on the outside port of your router. The "LAN" block will then be routed to that IP with the assumption that your router will pick it up and forward it to the LAN.

Theres a couple of ways you could handle this, you could set up your router to have two subnets on the LAN, the public block your ISP has given you and a private block. The router would then be configured to do NAT for traffic between the private subnet and the internet while leaving traffic to/from the public subnet and traffic between the two lan subnets un-natted.

Another option may be to have a single private subnet on the LAN and use explict NAT rules to map the additional public IPs to particular private IPs.

Whichever option you go for your router needs to be flexible enough to support it. If you have bought a typical home router it may well not have the options you need.