Windows – Attach third computer to shared internet connection

networkingwindows 7

I have 3 computers, all of which I want on the internet.
The first is a laptop, which has a wireless connection and an ethernet connection.
The second is a desktop, with 2 ethernet connections.
The third is a desktop, with 1 ethernet connection.
The laptop gets the internet from the wireless, and shares that on the ethernet connection to the first computer – this works fine. I want to attach the second desktop, so that it can have internet access.

I have tried to implement internet sharing on the first desktop, but it said it could not. I tried to create a bridge, but I was unable to get the internet on the second desktop.

How can I connect the second desktop to the first desktop, and have it accessing the internet?

Best Answer

Place an ethernet switch on the ethernet link of the laptop

attach both desktops to that switch

since you got no extra hardware ...

internet connection sharing (ICS) remains as it is on the laptop.

find out what ip subnet you are using. -> choose another 2 private nets e.g. and ... i'll refer to them as XXX.XXX.XXX.XXX and YYY.YYY.YYY.YYY

now configure the ethernet port on the laptop:
IP: XXX.XXX.XXX.1 subnet mask

ethernet port 1 on desktop 1 (connect to laptop ethernet)
subnet mask
default gateway XXX.XXX.XXX.1
primary DNS:

ethernet port 2 on desktop 1 (connect to desktop 2 ethernet port 1)
subnet mask

ethernet port 1 on desktop 2 (connect to desktop 1 ethernet port 2)
subnet mask
default gateway YYY.YYY.YYY.1
primary DNS

now you need to enable the IPRouting on desktop 1 ... for windows XP or 7 that would be a new registry key:
type dword
value 1

for a linux system ... echo "1" > /proc/sys/net/ipv4/ip_forward

(a windows machine needs a reboot after you enable the IP Router)