Static IPs for wired and DHCP for wireless - how?

FlakMagnet

FlakMagnet

FlakMagnet

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Joined
11 Dec 2006
Posts
179
Hi All,

My broadband comes with 5 static IP addresses which is great. The problem I have is that they are all used up now and I want to connect more wireless devices.

Could anyone tell me what piece of kit I need to buy that will do the following:

o Plug into my existing Router using one of the fixed IP addresses.
o Act as a DHCP server for any wireless devices I have in the house.
o Not need to be connected to my ISP - only my existing router.

I have had to set up my existing router to work with the static IPs that I have because my wife plugs a VPN router into it, and that MUST have a fixed IP for it to work. So I am forced to disable DHCP on my current router (that's the only way I can use the static IP that the VPN router requires).

If I set my router up to be a DHCP server, every bit of my equipment works fine! Just that the VPN router stops working.

So I'd like a piece of kit that would allow me to have DHCP for all my wireless devices, and static IPs for all the wired devices. I guess I can keep my existing router to provide the static IPs and interface to the ISP, but what do I need to connect to it to give me DHCP for my wireless devices?

Really sorry if that is difficult to understand, but I probably don't know the right words to use :)

Many thanks for any help!
 
Thanks for the info guys.

So if I understand correctly, I need an additional NAT router that can serve my wireless devices while taking one of the public IPs I have.

I think I understand how that would work - one static IP taken by the NAT router which dynamically assigns IPs to my wireless devices.

If this is correct, can anyone recommend one? I not sure that the cisco 8xx series is what I need is it?
 
I think that's ok. At the moment I have the following :

o ADSL Modem Router connected to BP with 5 static IP addresses.
o VPN Router plugged into ADSL Router taking up 1 IP address.
o Wifes' PC connected to VPN Router. Does not need to access any other machines on netwotk.
o 2 PCs connected directly to ADSL router taking up 1 static IP each.
o A bunch of wireless devices sharing the remaining 2 statis IP addresses.

I can only have 2 wireless devices switched on at the moment because I can't have their IPs assigned dynamically by the router.

So my plan now is to buy a WRT54GL or equivalent and assign another of the static IP addresses to it, plug it into the existing ADSL Router and let it service the wireless devices - assigning IPs dynamically to them.

As I understand it, the WRT54GL will act as a NAT router, translating the dynamic IP addresses of my wireless devices to and from the static IP address of the WRT54GL.

If that is correct, will I still be able to directly access my 2 wired PCs (with static IP addresses) from my wireless devices? Because of NAT, won't it look as if the wireless devices are on the same network as the PCs?

I guess I won't be able to connect from one of the wired PCs to a wireless device though as they will appear to all have the same IP address (the address of the WRT54GL).

Am I understanding this all correctly? It is a very confusing subject :P
 
Cheers, Moley. I actually think I understood all that :D

But am I correct in saying that you are limited to 4 wireless devices by NATing the dynamic addresses to your 4 remaining fixed? What happens if you add a 5th wireless device?

The reason I ask is because I'm only left with 2 static IPs on my Pix if I duplicate what you have done... but I have about 5 wireless devices!

I am thinking I can setup like below, giving me as many wireless devices as I like:

Code: 
                 <10.10.10.1>                    <10.10.10.2>              <192.168.0.x>
ISP|-----|[Outside]Router#1[Inside]|--+--|[Outside]Router#2[Inside]|-----[WirelessDevices]
                     and              |
                   Gateway            |   
                                      +--|PC#1 <10.10.10.3>
                                      |
                                      |   
                                      +--|PC#2 10.10.10.4
                                      |
                                      |            <10.10.10.5>
                                      +--|[Outside] VPN Router [Inside]|-----|[Wifes' PC]
Is that going to work?
 
Thanks m_cozzy. I think you are right about putting the PCs behind the NAT router too... should cause far fewer problems when getting the wireless devices to talk to the wired ones.

The only reason I wanted the PCs the other side of the NAT router was because I play games online, and I'm worried I'll have issues that I don't currently have to worry about. The second reason is that sometimes I connect to my PC remotely from work using Remote Desktop. If the PC is on the NATted side of the router, I won't be able to do this any more. But that is a feature I only use rarely, so might not miss it.
 
Have just ordered a WRT54GL (from OcUK) and should be here on Monday :)

Do people recommend changing to the Tomato firmware? or is the LinkSys firmware OK?
 
wij said:
To RDP into a machine behind your router that is getting an IP form the DHCP server in the router you could simply just set up a NAT redirect rule that would send the traffic to a set private IP address and then just fix your PC on a static internal IP.

Sorry that's not a good explanation but it's pretty straightforward to set up in most routers.

Give Tomato a go, adds a bunch of features you may find handy, DDWrt is also good for 3rd party firmware.
Click to expand...

Hey! Why didn't I think of that? Great idea wij (and I actually understood what you said - I must be learning stuff :))
I think that's what Moley was trying to suggest in post #9 above, but I didn't understand it then :P

OK, will give Tomato a go as have heard others giving it rave reviews.

Thanks again all!
 
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