I'm practicing with the Ethernet shield:
my first problem is: i don't have a router, I'm using a WiFi connection but i don't have access to the router, can I use my laptop as a router ? (just connecting the Ethernet shield to the Ethernet port on the laptop)
If is possible, I understood i should use a twisted cable , is that correct?
and then how can I set up the laptop to be a router ?
thanks to all.
What ever cable you use to connect your PC to a router (CAT 5), just use that. Do not attempt to smush a standard copper telephone cable in.
Ethernet cable is commonly a CAT 5 cable which is a standard of cable that utilizes a design called UTP (unshielded twisted pair), there are many variants like straight through, rollover and crossover. RJ45 is the connector used on NIC cards like the Arduino Ethernet. Category 6 cable is used for more fragile signals like gigabit Ethernet, whereas category 5 is used with megabit connections.
Most if not all cards these days support auto negotiation and will conform to whatever format of (CAT5/6) cable you use. Back in the day, hardware could be destroyed by using the wrong cable, apparently ( never had a problem in my time ).
OK I understood about the cable but, how can set up my PC to be a router ?
filippo47:
OK I understood about the cable but, how can set up my PC to be a router ?
Got any info about your pc? What is it you are wanting to do? Connect to just the pc?
ok ok , I'll try to give you some more information, my laptop is using a WiFi connection, (and i don't have physically access to the router, so i cannot connect the Ethernet shield to the router with the cable) .
I'm just asking if is possible to connect the Ethernet shield directly to the Ethernet port on my laptop, i suppose i should set up something but i don't know what.
the connector on the laptop is a RJ45 with a LAN Ethernet 10/100/1000.
i don't want to risk to burn something.
and Windows 8 running on the laptop .
You have to go to connections -> Internet Protocol Version 4 (TCP/IPv4) DblClick
PC Side:
and write the IP Adress: 192.168.1.2
Subnet Mask: 255.255.255.0
Default Gateway: Empty (if not try 192.168.1.1)
On arduino as above except IPadress should be 192.168.1.3
The only difference is the last number to be one up or one down e.g. on pc the ip could be 192.168.1.150 on arduino can be 192.168.1.149 or 192.168.1.151 and then from the pc on iexplorer or whatever you type the ip from arduino and there you are 
Good luck
Best Regards,
Tasos
thanks
I'll try .
An easy way to convert your Arduino ethernet to WiFi is to use a TP-Link WR702N Nano router in Client mode. You first connect it to your PC and join a wireless network, then you just connect your ethernet shield/module to it and you have a WiFi connection to the router signal you are 'borrowing' 
You can pick up the WR702N on ebay for about £15.
I have used this method for a while, its a nice and cheap alternative. Also very stable compared to the official Wifi shield as that does not properly support transport protocols and fails easily.
I have also wanted to try a router with multiple ports. Using an Ethernet to USB adapter ( for networked USB ) I'm hoping to be able to upload sketches remotely via Ethernet. Got my hands on an old goat (DSL-G604T) to test in the new year.