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I'm currently living in a location where I can have at most one MAC-Adress on the network. Nothing more is allowed by the rental agreement.

But for my study, I need more than one device on the network.

So I need some kind of bridge from the network of the university into a network in my room. I thought about using a router, or buying a second network card for my PC to achieve this.

The problem is, that I don't know how a router for example acts different than a directly connected PC from the outside. If I use a router, does that have any side effects for other machines on the outer network?

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The simplest solution is purchase a $20-30 router. Configured it to connect to the network. Connect PC to router. Your router is assigned an ip address by your university. Your router assigns ip address to devices connected to it. The two networks are unware of one another. This of course likely violates your network agreement. Your universities network staff can detect your using a router easy enough although less likely if its not wireless. – Ramhound Jan 17 '14 at 18:32
up vote 4 down vote accepted

Hmm, you will of course be breaking your agreement with the University by doing this and could get kicked off for doing so.

However, you would need something to act as a router as you say. This could be a router or could be a PC acting as a router - you need two network interfaces for this, the "outer" interface connects to the collage network, the "inner" interface (which could be Wi-Fi) is what your other devices connect to.

The router will translate all of the inner device addresses to the outer address (given to you by the university network).

There are impacts to consider. Nothing on the outside will be able to see the inner devices unless you configure Network Address Translation (NAT) in the router. Some services will not work with NAT but most do.

The other impact is that the traffic from your room is likely to be higher than average which may be detected by the network monitors and flagged. A clever monitor configuration would also be able to detect the apparently hidden inner devices using packet inspection. The only way to avoid that would be to run a "Virtual Private Network" (VPN) from the inner devices to somewhere outside the university network. There are public services that will do this but you will probably have to pay for them.

All told, you will never be sure that the university network monitors wont pick up your activities (well you might be sure if you get caught!!)

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To be fair, using a router to provide NAT / IP Masquerading means that you only are putting one MAC Address onto the WAN - that of the router. So if the terms of the agreement are to only allocate one MAC address, a router is exactly the right tool for the job and is not a violation of the 'one MAC Address' rule. – DopeGhoti Jan 17 '14 at 18:24
The thing is, we are all in one subnet, so one person could screw up the whole network for all other persons... High traffic is not the problem, I can shift hundreds of GB of data with 100MBit/s through the network to my friends. From you answer, I read that the router doesn't have any side effects on the other systems. The routers I know until now were all used for DSL, so they used a special mode where they don't act as a PC on the outside. Which mode should I select to do nothing like that, just carry packages and bind the WAN port to a specific custom user set IP? – Sibbo Jan 17 '14 at 18:30
Hmm, OK @DopeGhoti - you may be technically correct and maybe he will get away with it fine. I like your thinking - but I can't help feeling that he will still get kicked! Still, I'd be willing to bet that I would probably do the same if I was at University now. Of course, when I was, the Internet was still mainly in labs. – Julian Knight Jan 17 '14 at 18:30
@Sibbo, OK you may be fine then. You are correct that most hardware routers you will see in the home are DSL or Cable. However, that's just a convenience. The majority of routers have ethernet connections. You either need a router with an outward facing ethernet connection such as my Billion 7800N or to make your own router using a PC. – Julian Knight Jan 17 '14 at 18:33
Thank you very much. Your answer is definetly helping me. I think I'll buy a router now. – Sibbo Jan 17 '14 at 18:34

If you need to have more than one device for you studies, can you not ask the campus support desk if they have a 'best practice' for handling this scenario?

As far as the router with NAT, I would advice turning off DHCP and assign IPs statically. The fastest way to get kicked off is by having a rogue device advertising DHCP on the network.

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ah good idea. THis will ensure you wont be messing up the schools network.. little bit of a PITA to manage tho. – Richie086 Jan 18 '14 at 0:09
Well, the "campus support" are the admins that manage My network and they told me that I'd never be able to have more than one mac. They don't seem to be very cooperative. – Sibbo Jan 18 '14 at 9:49

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