Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

From my ISP I am getting one RJ45 Port from the Modem.

One IP adress is advertised by DHCP, but beside that I have an IP range I need to use for servers.

On the primary IP adress that is advertised by DHCP I need a router that connects hosts to the internet through NAT. But some servers should be assigned a static IP address from the range I got from my ISP.

Those hosts would need to be either on separate ports where NAT is disabled or the router needs to be configured to apply NAT only on hosts that are not from that range.

For the Port based solution the router would ideally have 8 Ports.

I am quite new to this and I hope my assumptions above are correct.

So my question is:

  • What are the specifications I have to look for when I want to realize a network infrastructure as described above?

  • What kind of network equipment would I need to solve this problem?

  • Is there an easier way like just putting a small Hub/Switch in front of the router and connect the hosts with static IP addresses directly to it?

share|improve this question
Joe, please at least mention the bandwidth the router has to handle. – petrus Jun 21 '11 at 13:10
we are connected to a 100 mbit peer, that is what the router should be able to NAT/Route. internally it would be nice if we get a good rate of gbit – The Shurrican Jun 21 '11 at 15:21
up vote 1 down vote accepted

You might take a look at SonicWALL and their line of products for at least a staring point. We have one configured exactly as you described and it has been "chugging" along fine for a few years now.

share|improve this answer
thanks will have a look at their products! – The Shurrican Jun 21 '11 at 15:21
If their physical specs meets your needs, their NAT implementation definitely will based on what you described... – user48838 Jun 21 '11 at 17:20

just putting a small Hub/Switch in front of the router and connect the hosts with static IP addresses directly to it?

Is a good solution (simple is nearly always preferable) - if you can be reasonably confident of the firewall implemented on the OS of the servers.

It'd be a good idea to set up at least 2 NICs in each server - one connected to the switch on the router side and one connected to your internal network (with a private IP, no routing between cards).

share|improve this answer
just thought it through with the the net address and broadcast etc, really seems to be a good solution – The Shurrican Jun 21 '11 at 15:21

A bit unclear, but it sounds like you have a set of static address given to you by the ISP. The cheap way to do it:

1) Attach the connect to the modem. Connect the servers to all the lan ports except one. Assign the static addresses to the servers.

2) For the last port, attach the port to the router and assign the static IP to the WAN port of the router. Then configure DHCP on the router to assign the private addresses for your hosts that needs to be on the private network.

share|improve this answer
sounds reasonable to me, probably better than a complicated solution with one single router. – The Shurrican Jun 21 '11 at 15:22

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.