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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?

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migrated from stackoverflow.com Aug 7 '12 at 2:32

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How're you connected to the phone system - do you have a 3G dongle on your laptop / a router plugged into the phone socket / something else? –  JohnLBevan Aug 6 '12 at 22:47
    
I have 3 computers running on a shared connection at home with no problems. You could be having COnflicting IP issues. Put "conflicting IP shared connection" in Google search... a bunch of articles on how to solve this will come up. –  Shenaniganz Aug 6 '12 at 22:47
    
The laptop picks up a wireless signal from a router. –  3Pi Aug 6 '12 at 22:47
    
@JonathonReinhart, I haven't used SuperUser, so didn't know. Is it possible to move? –  3Pi Aug 6 '12 at 22:51
    
A moderator can, I cannot. It may be just as easy to copy/paste and delete. –  Jonathon Reinhart Aug 6 '12 at 22:52

1 Answer 1

up vote 1 down vote accepted

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. 192.168.10.0/24 and 192.168.11.0/24 ... 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 255.255.255.0

ethernet port 1 on desktop 1 (connect to laptop ethernet)
IP: XXX.XXX.XXX.2
subnet mask 255.255.255.0
default gateway XXX.XXX.XXX.1
primary DNS: 8.8.8.8

ethernet port 2 on desktop 1 (connect to desktop 2 ethernet port 1)
IP: YYY.YYY.YYY.1
subnet mask 255.255.255.0

ethernet port 1 on desktop 2 (connect to desktop 1 ethernet port 2)
IP: YYY.YYY.YYY.2
subnet mask 255.255.255.0
default gateway YYY.YYY.YYY.1
primary DNS 8.8.8.8

now you need to enable the IPRouting on desktop 1 ... for windows XP or 7 that would be a new registry key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
IPEnableRouter
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)

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Sure, this would work, but relies on having a spare switch. I have a spare ethernet cable. –  3Pi Aug 6 '12 at 22:49
    
See my conflicting IP comment. You're assigned one IP address by your Internet provider therefore having multiple computers without having a router split it will block you from the Internet. Without having an extra router you need to manually program IPs into your PCs under TCP/IP settings. –  Shenaniganz Aug 6 '12 at 22:55
    
@3Pi see edit ... –  DarkSquirrel42 Aug 6 '12 at 23:04
    
Thanks, that's exactly what I was looking for. –  3Pi Aug 6 '12 at 23:49

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