Setting a Modem-Router as Access Point problems

[geg_thomas]

Hi all, long-time reader, first time poster...

There's a TL;DR question at the end that people might be able to help me out with, simply about buying a dedicated AP.

Currently having trouble trying to set up a wireless network for myself at home, using a D-Link DSL-2730B Modem-router (seems common in Aus/NZ but USA site doesn't have any info on it).
It's a bit convoluted, but basically I live in a studio room (similar to a dorm I guess, but fancier) in a house that has a wired internet network. There is a modem-router *somewhere* in the building that everyone connects to, which isn't wireless (massive house, thick walls in any case).
Had the IT guy who connects everyone up come down and try to set me up. The way it works is that at his end (i.e. the main router) he manually allows people to connect via the MAC address of whatever it is they're using (like their laptop. The connection is metered as everyone has a personal data allowance). He said being able to use my router is theoretically possible, but couldn't figure it out himself after extensive tries. He manually added the MAC of the router to the main router, which works. He added my laptop and Xbox MAC addresses to the main router, and can successfully connect to the internet directly from the ethernet cable that is in my room.
One of the many problems is I have a myriad of wireless devices, and where my desk & laptop is setup is beyond the length of the cable, which wouldn't matter so much even if it weren't, because I want to have multiple devices connected at once...

So with the actual setting up of my router in regards to the main router, the problem there is that I have no control over the main one. I can't login to it (with good reason) and change settings or anything, and I don't even know the make/model. All I do know that it's IP address is 192.168.0.1.
I've researched various walk-throughs (used this one the most), threads on this forums, youtube videos and other sites, and it seems the consistent instruction is as following:
The instructions recommend setting up the SSID of the wireless network, which I know how to do in the past from living elsewhere and managing the modem directly.
Next is to disable the DHCP of the access point as the main router will deal this out (supposedly).
Then it's to assign the router-AP as an IP on the main routers network but not on it's DHCP range- which i've gathered from connecting my laptop and Xbox directly starts at 192.168.0.100 as they were assigned ones like 192.168.0.104 and 192.168.0.118. Mostly I set it to 192.168.0.54 or 192.168.0.99
Then soft reboot, connect ethernet to one of the router-AP's LAN port (it has no WAN port so I'm at least not making that mistake!) and connect.

I've tried these things in its simplest form, and can connect via wired ethernet from another LAN port to my laptop, but not wirelessly to the internet. I can see the network, join, be connected, but it won't connect to the internet (no sites loads- depending on what configuration I'm trying out some say 'limited connection' or has full connection but no websites load and no services connect).
If I leave DHCP enabled (and set it a range something like 192.168.0.55-99 not including the router-AP address) I can connect wirelessly and to the internet on my laptop but not anything else. I'm not sure why my laptop can and my other devices- Xbox, WDTV Live, Samsung Tablet, Samsung phone or iPod Touch cannot connect to the internet. I thought perhaps simply because my laptop had been allowed via its MAC address on the main router, but then my Xbox was as well and it won't connect. Then I realised that the MAC address assigned on the main router was my laptops ethernet MAC address and not my wireless hardware one (this is how little I know: I didn't know my laptop had two!) yet it still connects.

I've tried assigning all the other devices static IPs in the range outside of what I think the main router is (100+) and even tried in that range just to check if it'd work, and it didn't.
I've tried creating an internet connection on the router as recommended by one tutorial making it a 'bridge' connection but I don't think it makes a difference.

The things that occur for the devices that aren't my laptop are:
Connects to the network OK, doesn't see internet connection OR
Connects to the network OK, has internet symbol as connected but nothing resolved -which makes me wonder if it's simply a DNS issue? Looking at my laptop's config for when it does connect, it says its DNS is the main routers address of 192.168.0.1, which I've tried assigning manually on my devices, but when I try to load a page it directs me to my data quota tracking page and nothing else. I've tried setting the router-AP as the DNS server but it doesn't work. Tried setting google's DNS of 8.8.8.8 (on the devices AND on the router in advanced settings) as well but that hasn't worked. I don't know my ISP or it's DNS. However from what I can gather this shouldn't be the problem???

Some tutorials have recommended leaving DHCP assignment ON on the router-AP, and setting it outside the main routers field. When I've tried this, the laptop can connect to the internet but again, nothing else will. The devices are assigned IPs in the range but still won't connect. oddly, the IP my laptop is assigned is not on the range I specify and instead has one assigned by the main router- usually .104 or .114 or .118.
When DHCP is disabled I connected my tablet and iPod to the network and looked at their IP addresses that they were assigned, and they cycled randomly through combinations like 192.256.77.5 or 192.1.222.70 or stuff like that. So whether DHCP is set or not, my laptop seems to be getting the same address from the main router when connected wireless, and not from the AP-router? The other devices never get assigned an IP thats consistent with what the main router gives directly from it's ethernet cable (the 100+ range) which makes me wonder if the devices aren't getting any further than my AP.

I've tried lots of combos and have a million notes written down to the point everything is confusing, which is very unhelpful because it means I can't accurately describe to you all what I have and haven't been doing! So my deepest apologies for that. I have some screenshots of the settings of my laptop (ftr, an Acer Aspire 5560, 4gig RAM) and the router (the usual settings recommended).

I confusingly got a screenshot of the laptops wired LAN connection details, but Im 99% sure the only difference is the name of the hardware, physical address and the IP ended 118

TL;DR question: the IT guy said if I bought a regular access point it would work, and all he'd need to do would be to add it's MAC address to the main router. I've located two affordable models and was wondering which would be better (one says extender and the other access point???)

http://www.mightyape.co.nz/product/TP-Link-TL-WA730RE-150Mbps-Wireless-Range-Extender/21010896

and

http://www.mightyape.co.nz/product/TP-Link-TL-WA701ND-150Mbps-Wireless-N-Access-Point/21010893


Sorry for the mish mash of information; there's probably a bit I've missed out but typing this out at work I can't remember everything from last night... I have a feeling I might be doing something really basically wrong or that simply it's not possible-or easily possible- with the model of router I have???

Thanks in advance!

 

[Urumiko]

Hi m8, thats a rather concise post so I shall try and give you a concise answer,
Though it may turn out to be just as long.

Firstly some quick theory...

Ethernet framing, and IP packets, - or the diference betweena switch and a router..

Ethernet sends messages in "frames" which use mac addresses to find their way round a network, every frame has a source and destination address.
basic switches dont know anything about ip addressing and work purely with mac addresses and frames.
when working purely with switches a frame will move from one end of the network to the other labeled with a source and destination mac address that stays the same.
A network populated entirely by any number of switches is considered one flat/complete/all-encompassing ethernet network, and strictly speaking doesnt even need ip addressing for all computers on the network to talk to each other, as they can use mac addresses.

once you bring routers in to it this is very different. Routers are all about IP packets which are encapsulated/carried within the ethernat frames, the clue is in the name "Internetwork Procol (IP)".
if you have two independent ethernet (switched) networks and want to connect them rogether you use a router.
On a router each interface is considered a boundary between a seperate ethernet network, as opposed to a switch where all interfaces are on the same network.
Why is this important?

well.. as I already said when a switch passess messages accross a network the source/destination mac address stays the same, however mac addressing can only be used to communicate with devices on the same network.
With a router, you are taking a message from one independent network to another so the mac addresses will have no relevance on the destination network and have have to change at some point.

Imagine a router with 2 interfaces and a switch hangng off each interface, & computers connected to each switch. The 2 switches are on different ethernet networks, lets call them A and B.
If a computer on network A wants to talk to a computer on network B via it will send out a message which contains source and destination mac addresses, and ip addresses.
The ip addresses used will be the source and destination computer, thats easy enough, but what about the mac addresses? They can only handle communication within in the same ethernet network.

When the message leaves the computer on network A it will have a source mac of the computer sending the message (as you'd expect), but it will have the destination mac of the routers interface (default gateway) on the same network, not the computer on the other network.
when the message gets to the router, the router will stop paying attention to the mac address, and look at the ip (internetwork) address. It uses this to get the message from one network to the other by routing. When it reaches the other network, (on the 2nd interface), it exits that interface still with the same source/dest IP address but the router uses different mac addresses.
The source mac will be the routers interface on that network and the destination will be that of the PC on network B.

Why am i telling you all this?? well..

What you have to remember is home "routers" are actually several devices glued together in one box,
at the very least it can be viewed as a propper router, and a seperate switch with both wired, and wireless connections hanging off it.


The router, in your box typically has 2 interfaces, one is the wan/internet facing interface, the other is internal.
The internal interface is then connected internally to a switch, the ethernet ports you connect your computers to are actually other ports on this switch.
For the purposes of this we'll assume the wireless is just part of this switch, it is just another means of connecting in to this same switch.

Lets assume you have your "router"s wan port connected to the building internet.

If you think about a message leaving your computer destined from the internet in the context of everything said so far, you will note that your messages are passing not just through the switch part of the box, but also the actual router bit.
if you think about it this means all messages leaving your router destined for the outside world would have the same mac address as they have crossed from one network to another via a router, which is great from a the perspective of allowing mac addresses through. They would only have to allow the mac address of your router.
all you would need to do is configure the WAN port on the router to receive an ip via DHCP from the building router. Happy days right?
Well yes from an ethernet/mac perspective but....

The problem is to make things work in this way at an IP level, you have something called NAT (network address translation), which allows all of the ip addresses/devices inside your appartment network to share the routers one internet facing ip address and communicate with the outside world via a "one to many" configuration.
The problem with this one to many nat as i understand it is that if you use it in one place in a chain of devices you cannot use it again in the same chain. As your buildings router will use this NAT system to allow you all to access the internet, you cant use it again higher up in your appartment.
If you do it will either be slow, or work for some things and not others etc.

The usual way to get round this is to connect the building router to your LAN ports instead, and turn off DHCP, effectively bypassing the router bit and using it as a wireless switch, (or only using the switch part of your box).
This gets arround the NAT problem by allowing all your devices to communicate direct with the building router via the switch portion of your box. The problem is that now all of the devices are on the same ethernet network, so the building router/switch, can see all of the different mac addresses and deny them according to it's security policy.
Devices conencted to the wifi are generally tret as if they are connected to the switch also, so again there mac addresses are visible.

I can't see an independent access point being a solution unless it is configured to be controlled by the building network which would be a big job/design change to configure. if it is operating independantly it still has the issue of either all the mac addresses being visible to the building router, or having to use NAT to function as a router with its own network like what you already have. It might provide some king of bridging function where everything that comes out of it would be on one mac address but im not convinced without trying.


You basically have 3 options that i can see:
1: The simple one is to ask the building if they are willing to divulge or change their policy sligtly, for example rather than explicitly allowing specific devices, they could limit you to say 10 devices at a time, theres no real reason to specify devices explicitly as you can change your mac address to one you know is allowed anyway, this is very simple switch config. I can only assume they are manually trying to keep track of how many devices are in use.
If you could be bothered you could just keep track of the allowed mac addresses then change all your devices to these, you just couldnt use 2 devices with the same mac at the same time.

2: Another solution in my head, which they probably wouldnt be willing to do as its more drastic than changing the mac policy, is to keep your appartment with its own router/ip range/dhcp pool, but add a static route in to the building router t allow it to direct traffic destined for your ip range to your router.

I guess really you need to ask them what it is they are trying to acheive with their policy and see if you can find a common ground, because most of the sensible solutions involve them making simple changes to their network design.

Just out of curiosity what other options do you have in the connection type drop down box that currently says brifging?

 

[Urumiko]

oh and, as for the wireless kit, I generally recommend the tp-link stuff it does what it says on the tin for a good price.
AN access point will have full fledged features for controlling things like authentication, and probably dhcp and stuff as well, and will ultimatley provide wireless access to an existing ethernet network.

an extender is designed to relay the wireless signal of an existing access point to cover a greater area, they sometimes have extra ethernet ports to give you wired access in a remote location too.

 

[boosted1g]

If the building/dorm wont do anything for you (doubtfull they will) then the only thing you could try with any possible success due to their port security is to get a standalone wireless router (not modem/router combo device) and configure its mac to be the mac you gave them, and configure dhcp to be a on a different subnet then the 192.168.0.x and then set the DNS to be 192.168.0.1

 

[geg_thomas]

Hi m8, thats a rather concise post so I shall try and give you a concise answer,
Though it may turn out to be just as long.

Thanks for your lengthy and detailed reply! Helped me greater understand how this all works. In the end I've ordered a TP Link AP and the network manager has confirmed he can whatever changes are needed to get it to work. Would've loved to have made the router work though, but a dedicated AP seems much simpler in the long run.

I think your explanation of ethernet and routing should be kept for posterity though. Very informative!!

 

[Urumiko]

no problem. Let me know how you get on. I'd be interested to know if it works.