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[tickmike]

I'm going to try get an secondhand Free wifi router from 'freecycle' (or other place  ) to be used in my daughters uni flat so she can use the internet on her phone.

I wanted to know if they can all be configured or are some locked to an ISP's settings and can not be changed by me.

[kitz]

Some are locked to SPs (ie sky), but the main problem could be DHCP depending upon the uni set up (and whether they allow) 

Normally id ensure that the subnet is the same & assign the AP router an IP in the same range as that in the uni range of LAN IPs and make sure DHCP is disabled on the the AP

[sevenlayermuddle]

Some are locked to SPs (ie sky), but the main problem could be DHCP depending upon the uni set up (and whether they allow) 

Normally id ensure that the subnet is the same & assign the AP router an IP in the same range as that in the uni range of LAN IPs and make sure DHCP is disabled on the the AP

Hmm,

Choosing that IP address could be a challenge.   

The trouble is, if you choose one that happens to be already assigned, or one that Uni's DHCP server subsequently assigns, then some other bit of kit connected to the Uni LAN might stop working, might it not?   That might make their IT admin staff slightly agitated.

Ideally I suppose, the router should get its own IP from the Uni's DHCP server, but I think routers generally need a fixed IP?

[tickmike]

I know it's done as one of her flatmates does it and yes it's officially not permitted in her private halls   .
Edit ... It's a fix IP from there system (Mnet). Thinking about it must be DHCP and not fixed because I think I have seen different address's
I was thinking to put that on one of the routers RJ45 sockets and have another one from the router feed her laptop and then have the WiFi on with security for her phone.
If I had the Router DHCP on another sub-net. it could not only then supply her laptop and phone but her mates laptops / phones as well when they sleep over ?.
Would that work ?.

[burakkucat]

I'll answer that with a cautious 'yes'. 

Essentially Ms Tick has an RJ45 socket in her room which supplies the NAT'd service from a DHCP server over an Ethernet cable.

You will need to set up that proposed subsidiary device to take the output of that socket as the source to its own DHCP server. I.e. its own DHCP server needs to be the DHCP client to that which emanates from the wall socket. You are going to be in the realms of both double NAT'ing and double DHCP'ing. Once everything is working on that LAN via Ethernet cables, you will then have the fun of turning on the WAP and ensuring that it is secure -- so that only authorised devices can make use of the bandwidth.

[sevenlayermuddle]

I'll answer that with a cautious 'yes'. 

Essentially Ms Tick has an RJ45 socket in her room which supplies the NAT'd service from a DHCP server over an Ethernet cable.

You will need to set up that proposed subsidiary device to take the output of that socket as the source to its own DHCP server. I.e. its own DHCP server needs to be the DHCP client to that which emanates from the wall socket. You are going to be in the realms of both double NAT'ing and double DHCP'ing. Once everything is working on that LAN via Ethernet cables, you will then have the fun of turning on the WAP and ensuring that it is secure -- so that only authorised devices can make use of the bandwidth.

This is an interesting topic, but I remain to be convinced.  As I see it, yes, the router's NAT service could indeed provide such a service, if the public side of the NAT could be connected to the Campus LAN.  But there is no access to the public side of a router's NAT, other than the ADSL connection, which cannot be connected to a LAN.

My reasoning is that the router will have a static IP address, typically something like 192.168.1.1.  If that is then connected to the Campus LAN then there is no way of knowing whether it conflicts with another IP address, assigned either by the Campus DHCP or by the Campus IT dept.   If it does not conflict it may work for a while, but conflict may arise later.  Even if it does conflict it still appear to work, since the router is only routing, and doesn't need to respond to any IP traffic.  And if there is conflict then somewhere else on the Campus LAN there will be another system, which has been assigned the same IP address, and that other system may then cease to work properly.

But I may be missing the point of this somewhere, always happy to be proven wrong 

Having stirred things up a little I will now be silent for a day or two as I'm off on an errand.   Interested to follow any comments, though.

[kitz]

Im not too sure about double NATing, as far as I can see the main problem is _always_ going to be the LAN IP on the first router (AP) that you connect to the RJ45. 
Any devices connected after this router(AP) dont need to be fixed and can be allocated via the uni LAN DCHP device. 

This device(AP) would need a static IP within the same range as the uni LAN.   It doesnt need to be 192.168.1.1 but it would need to be in the same range and physically assigned to the router(AP).   You cant just guess either because theres a likelyhood that it will cause a conflict elsewhere.

I wonder if you could trick the system, ie get an IP on the laptop via normal means and then quickly assign that IP to the router(AP).  Turning DHCP off on that router(AP) then ensures that the uni router will assign any LAN IPs that subsequently connect to the AP - either via the cable ports or wireless.   

How long this would work for depends on whether the router was ever turned off and the lease time of IPs on the uni LAN.

Im now tossing ideas around...

Would a proper wireless access point not work better?  7LM could perhaps comment, but my understanding is that AP's can act like a network switch on the datalink layer (using MAC addresses) and can use DHCP from the uni router to get an IP for the wireless device* APs are specifically designed to work as an extension of the existing network.... whilst routers operate on the Network layer (using IP addresses) and can (usually do) act as a DHCP server in their own right.

Yes its possible to use old routers to act as Access points by utilising the switch and wireless components within it, but it needs to be allocated a LAN IP, because it cant do it itself.  We normally recommend this method because its a cheap way of using old routers without having to fork out for a 'proper' AP.

Not sure about this but could another option could perhaps be to create a wireless ad hoc network?  Ive done this before on a Windows XP machine using Windows ICS but I havent a clue how it would work on a Linux system.



*More advanced standalone APs also have the options to act as DHCP servers and can be configured to do so.

[tickmike]

Thank for kicking idea's about 
Well yes I have tried an Ad-Hoc network, after spending loads of time sorting her old laptop to work like this  as a test to another computer.
I use Linux as you know so I did this

In in a Terminal su to root/password, use these commands to set up 'iptables'     (Firewall)

echo 1 > /proc/sys/net/ipv4/ip_forward

iptables -t nat -I POSTROUTING -o eth0 -j MASQUERADE 

service iptables save
service iptables restart

To check
chkconfig --list iptables
 iptables -L
Set up a 'script' to run at boot to do above.
Set up static ip's etc.

It worked well.
I set my daughters new laptop last weekend when she came home and it shared the internet with her old laptop very well , taking her back on Sunday I set her laptop up then tried and tried to get it to connect to her iphone 4, tried setting up a static ip address, it seemed to connect but it would not go on the internet.
I could not find a way to set up 'Gateway' and DNS on her phone.
Looking on Apple support forums there seems to be loads of people having problems connecting to a Ad-Hoc network.
She has no problems connecting to our home network access point with her phone.
I told her not to get an iphone 

[sevenlayermuddle]

  7LM could perhaps comment,

I didn't intend to present myself as the authority, rather the sceptic.   Still I'd love to comment and may do so in time 

but my head's in a spin over various unrelated things that are going on, unlikely to comment further, feel free to disregard my earlier mutterings. 

[kitz]

>> I didn't intend to present myself as the authority, rather the sceptic.

Noo..   Sorry, it  was more I was spouting off the top of my head... and with a name like 7LM I thought you may be more qualified than me to comment on the 7 Layers of the OSI,    as to whether if a 'proper' AP rather than a router would be easier to configure because they work at the datalink layer.
 
I must admit its >10yrs since Ive had a 'proper' AP as Ive since used the cheapy option of old routers so I may be wrong,  but they are much more forgiving about IPs as their aim is to act in a similar way to a network switch when it comes to traffic, so therefore they can be assigned an IP outside of the LAN pool, yet still work & allowing data to pass through.

Obviously you would still need to configure it, but this could be overcome by temp setting a PC to the same range as the AP to access the config pages.  As long as the IP assigned to the AP is NOT within the same range of those normally assigned by the uni's DHCP server, then there shouldnt be any conflicts?

I am happy to be corrected,  but I would have thought it would be easier to achieve what it needed using a proper standalone AP, rather than trying to get old routers to 'act' as APs, purely because they dont need an IP assigning that is within the available LAN pool.

I - like you - have some doubts if double NATing would work, because unless Ive missed something, it unfortunately doesnt overcome the problem of how the first router (which works at the Network layer) could automatically be assigned a LAN IP. :/

[kitz]

Actually...  and on reflection...  I wonder if you could trick the router into acting at the datalink layer.
Im not sure if this will work, but in theory it should.

In other words manually assign it a LAN IP outside the normal uni LAN range.   
Make sure you turn off DHCP on the router.  To configure the wireless settings on the router, temporarily assign the laptop an IP in the same (outside) range as the router.

Plug the router into the RJ45 port.
Now change the network settings on the laptop back so that it is as it was if you werent using the router and plugging back straight into the RJ45.
Plug the laptop into the router's switch ports
Hopefully now the router will be acting as a switch only and the laptop will pick up an IP from the uni DHCP server.
Any wireless devices should also pick up IP via the uni DHCP server which will also be performing the NAT.


The old router is now acting purely as a network switch for traffic flow.   Its not part of the uni network and performs no network layer functions.  The assigned IP is only there so that wifi security can be set and can be ignored otherwise.

Thoughts anyone?

[burakkucat]

  Hmm . . . Yes, certainly worth a try.

This whole scenario is very much 'suck it and see'. 

[tickmike]

Had an offer of a free router, still trying to get some info about it.

My daughter is going out helping with the Lambing today and she just sent me some details of her laptops assigned IP's


At the moment the IP is 10.210.10.39, Gateway: 10.210.10.1 and DNS: 10.100.100.10 which looks like it's is used as private address space, so yes double Natting may be a problem.

I did sent an email to 'Mnet' (the private halls ISP suppliers) but not had any reply yet.

Edit.. I think it's on a 50:1 contention ratio.

[kitz]

I dont think it will be anything to do with Mnet as they will only provide the internet service.   Mnet wont care much as long as they get paid.
It will highly likely be down to someone to configure the internal network rather than the SP.... and therefore its they who will decide which IPs are used on the LAN. 

>>> it's is used as private address space

These are just reserved IPs used for private (internal) networks. If the halls are using the 10.x.x.x range (which is massive) and looking at the IPs  possibly subnetted....  then afaik there shouldnt be a problem if you use one of the 192.168.x.x for an AP as suggested above 

[tickmike]

I have been pointed to these .

http://www.misco.co.uk/product/195205/

http://www.dlink.com/uk/en/home-solutions/work/wireless-mobile-broadband/dir-505-shareport-mobile-companion

Anyone use one  ?.