11-Networking Continued: Layer 1
- When I refered to layer 0 in the last podcast, I meant layer 1
	- oops
	- sorry
- I said i wasn't going to talk about layer 1 anymore, but I changed my mind!
- Most of layer 1 we don't care about
	- One thing we do care about
		- ARP
			- Address Resolution Protocol
			- Mapping between MAC Addresses and IP addresses
			- OLD
				- thus, no security
		- All IP traffic is sent around by MAC Addresses
		- Whenever a machine needs to talk to another machine, it says to every machine on the network:
			- Hi, i am this MAC Address, and i would like to know which MAC address has the IP address xxx.xxx.xxx.xxx
			- All the machines look at the packet, and say, Nope. not me
			- Except the one that does have that IP address
				- it responds saying:
					- I am this MAC address, and My IP address is xxx.xxx.xxx.xxx
			- The original machine then makes an entry into an ARP table, and maps that IP address to that MAC address
				- Then whenever it needs to send information to that IP address, it looks into that table, and sends it to that MAC Address
		- At no point is there any security in this process
			- ARP Poison Routing
				- Makes open wifi very dangerous
				- Sends out a packet saying
					- Hi, I am this MAC Address, and  i have  the IP address of the router
				- thus all the traffic that would go to the router gets passed thru this machine
					- both incoming and outgoing
				- Anything unencrypted they can see
- Commands
	- tcpdump
		- prints all network traffic
			- with their protocol
		- need root access
	- arp -a
		- shows the ARP table
			- which mappings the computer has
- Bart Busschots
	- bartb.ie <http://bartb.ie/>
	- impodcast.tv <http://impodcast.tv/>
	- podfeet.com <http://podfeet.com/>