network bridge vs internet sharing

[mike perez]

anyone know the difference between Bridged Connection and Internet
Sharing in windows 7? I had been trying to bridge my wireless and
wired connections all night to give internet access to a desktop with
no wifi adapter via crossover cable from my laptop. (i believe
crossover cables arent needed anymore in modern ethernet adaptors but
this is an old desktop). Bridging the two connections did set the
ethernet IP on the desktop but i could never ping or access anything
on the internet. Then i stumbled onto "internet sharing". I removed
the bridge and enabled sharing. Bam, internet connection. So what's
the deal with Bridged Connections and internet sharing in win7? By the
way, i had also disabled the windows firewall before making the
bridged connection.

[Nick Borko]

I don't know about Windows 7 specifically, but at least since XP
bridging has been purposely limited to force people to buy Server
editions and associated internet appliance products.

Nick

[mike perez]

gah! should have known. embrace, extend, extinguish

[Jordan Rinke]

The comment about it being limited to force people to buy server editions is not true at all, especially since we are talking about a client OS here (The closest to factual information would be that the Web and DataCenter edition of the Server OSes don't include ICS/Bridging). Bridged networking is not limited in any way. It is a direct pass through bridging the two adapters, directly forwarding packets between them making it appear as a single subnet. ICS implements a NAT between the adapters to the guest systems. Depending on what nic/switch/router you are using it may not have tolerated multiple MAC's coming from the same port, or it may not properly support forwarding when you had bridging setup. With ICS it appears to only be a single host since it adds it's own NAT layer.

A lot of people use Windows 7 laptops etc to bridge connections with Wired/Wireless to play their xbox so they don't have to buy a separate wireless adapter just for it. (popular in door rooms etc)

[mike perez]

Hi Jordan,

yeah that's what i had figured. I wasn't using any hubs/switches other
than the wireless AP. I thought it should have been a simple pass-thru
from laptop to desktop. Initially, i had setup the desktop eth and
laptop eth to be on a different subnet than the laptop wifi. The AP
served up DHCP. At some point i even set the gateway to be the laptop
wifi IP address. But still nothing. So i changed both eth devices to
be auto-dhcp. This time when i bridged the eth to wifi all three net
devices had the same IP on the wifi subnet, that is, the wifi and eth
on the laptop and the eth on the desktop. Still couldn't ping out from
the desktop. Though all this i never had a problem going out from the
laptop wifi card.

Anyways, its very puzzling because many moons ago i had used these two
machines in a similar fashion. I was using the windows laptop to
netboot linux onto the desktop. Then, i needed the laptop to act as
web proxy for the net boot image to download packages. Instead of
configuring things thru the OS i used privoxy which a personal web
proxy you install side by side with your browser of choice. Instead of
listening on 127.0.0.1, i set the proxy to listen on the laptop's eth
IP which was on a different subnet than the wifi. This all worked then
but not last night. That's when i started down the road to bridging
the networks which i've done many times with VMs bridging virtual
network adapters to physical adapters so i figured i understood the
concept. man that was a frustrating night, last night.

[Nick Borko]

I was just paraphrasing what Microsoft Support told us 10 years ago;
if you wanted to do what you're saying, they said you had to buy
Server and their internet connection management server, which I don't
remember the name of, and that it wasn't supported in XP. Though I'm
pretty sure the stack was complete, and you could do it with 3rd party
software.

Nick