Let's talk a little bit about putting a computer on a network!
	I will try to remember to bring my laptop today
	If I forget, we'll just do our best

ifconfig:
	We've been parsing the output forever
	ifconfig to bring interfaces up or down
	Setting a MAC address
		- Why?  Usually to impersonate a different computer

route:
	Usually you run this:
	route add defaulg gw wherever_your_gateway_is
	Can make other routes, depending

DNS:
	/etc/resolv.conf
	That's where the nameserver goes

The more automatic way:  dhclient
	dhclient interface
	dhcpcd is sometimes around instead
	Depends on a DHCP server being present and willing to talk
		- You can run your own DHCP server if you like

Wifi:
	iwconfig and iwlist
	For a "polite" network, that's all you need
	Trust has been on the decline
		- Lots of people won't give a stranger a lift either
		- A few ruin it for the rest
		- Were you there for CS101 augmented reality?

wpa_supplicant:
	And lcsc config example
	Other types of authentication work differently

Is this too much work?
	wicd
	NetworkManager
	Connect to strongest AP?
		- Most people run their systems that way
		- Strong cards and WWU VU
		- Hostap

Drivers!
	Usually these aren't a problem, but they can be
		- Linux on macs (why?  Why not?)
	Chipsets
		- There's nothing new under the sun
	It used to be a good idea to verify compatibility

Making your computer a firewall/DHCP server/NAT/Router/etc
	Example on nimrod
	I do this with orcrist sometimes
		- MAC addresses and dorms
	jen, fwstart scripts
		- These probably don't work on FreeBSD

How fast are networks really?
	Bandwidth
		- a byte is 8 bits
		- half a byte is a nibble (not joking)
		- Bandwidth can be rated in bits/second OR bytes/second
			+ Gb = gigabit, GB = gigabyte, don't trust this
		- SI prefixes, kind of
	Latency
	Think about this when you decide to do something over a network!
		- LAN
		- Cable and DSL, wifi
		- Cell network
		- Dial-up
	Internal computer interfaces are faster
		- Main memory, FSB, PCI-Express, etc
	Proprietary stuff is out there too
		CrayLink / NUMAlink

"gateway of last resort" term:
	ChatGPT says it's the default gateway

Actually using a computer as a router
	Note:  There are OS features to make this easy (connection sharing, etc)

Demo of using a laptop as a router

Piece of the puzzle #1:  How are you going to see what I'm doing?
	First:  The projector!  Hopefully this is working already
	Second:  We can SSH into it so the screen share looks good

Piece #2:  Connecting them together with a little subnet
	We'll give each of them an address in 172.16
	Can they communicate?  (hopefully!)
	
Piece #3:  Putting ocrist online (might already be)
	We'll do this as manually as possible!
		Automation hides the details
	wpa_supplicant to handle the WPA authentication
	Then we'll use dhclient to run DHCP
	Let's see what we ended up with for a routing table (netstat -r)

Two ways we could go from here:
	Bridging:  Just send traffic back and forth without change IP range
	NAT:  Have a different IP range on each side of orcrist

Piece #4:  Using NAT
	We could set gateway_enable="YES" in rc.conf to turn this on all the time
		I don't want to
		Makes it easy to cause a weird problem
	sysctl net.inet.ip.forwarding needs to be set to 1
		There's a /proc file in Linux that'll do the equivalent thing
	Setting a route to the little network isn't really needed in this case
		Because we're directly connected to 172.16
	So we can talk to either the Internet or our other computer!
	/etc/pf.conf and pfctl
	Run like this:  pfctl -nvf /etc/pf.conf
		Take out "n" to have it actually add the route
		Good to verify first!
	A suggestion from the FreeBSD Handbook:
		ext_if = "xl0"	# macro for external interface - use tun0 for PPPoE
		int_if = "xl1"	# macro for internal interface
		localnet = $int_if:network
		# ext_if IP address could be dynamic, hence ($ext_if)
		nat on $ext_if from $localnet to any -> ($ext_if)
		block all
		pass from { lo0, $localnet } to any keep state
	Does it work?  (who knows!)

Piece #5:  Not using NAT
	Bridging:  Basically, we'll just pass traffic through in a transparent manner
		Our presence will be invisible!
	ifconfig bridge create
	ifconfig bridge0
	ifconfig bridge0 addm wlan0 addm em0 up
	(and have both interfaces actually up)
	Bridge can have an IP address if we want it to
		Do we?  Probably
		Will this work?  I couldn't get it to work with wifi, but I'll try wired

Couple other things we could do:
	Since the switch ports aren't set to trunk (probably), we can't play with vlans
		Could otherwise - Linux and FreeBSD are happy to play ball
	STP/RSTP:  Linux and FreeBSD are again happy to play ball
		I doubt the switch wants to, certainly not the AP

Alright, we've put orcrist into the middle in a couple configurations
	Let's run wireshark on ocrcist and spy on the other computer!

Could you use this in other ways?
	Sure!  We could, for example, set up our own wifi network
		Just need another card