mccNov 18, 2022

I have a Windows 10 machine with two Ethernet interfaces. For Important Reasons I want to share internet from interface A to interface B. I cannot figure out how to do this. There are multiple control panels governing this, showing non-overlapping sets of information. There are multiple guides on the Internet, some of which I have followed the steps in to no avail.

What I'd love is a list somewhere of what's being shared from, what's being shared to, and on which connections DHCP is active.

Show threadmccNov 18, 2022

My network topology is
[Windows 10 machine] -> usb ethernet adapter -> crossover cable -> usb ethernet adapter -> test mac [will later be replaced with an important internet appliance]. On the test mac, DHCP doesn't seem to work [I'd prefer DHCP if it were an option] so I've manually assigned the test mac IP 192.168.137.2 and given 192.168.137.1 as gateway. It claims the LAN is active on the test mac, but apps cannot route to the Internet.

I do not know how to proceed.

Show threadmccNov 18, 2022

Update: I realized I actually have a bit of an A-B problem here since what I'm REALLY trying to do is share my NordVPN connection to the Ethernet adapter. I then found there's a guide for this on NordVPN's site!

https://support.nordvpn.com/Connectivity/Windows/1047409882/Sharing-a-VPN-connection-through-an-Ethernet-cable.htm

I followed the instructions and it doesn't work.

Show threadmccNov 18, 2022
UPDATE: I HAVE DISCOVERED THE PROBLEM. AS ANYONE WHO HAS USED A COMPUTER BEFORE WILL BE ENTIRELY UNSURPRISED TO LEARN, THE PROBLEM WAS A BAD FUCKING ETHERNET CABLE
Show threadmcc
I bought this ethernet cable off Amazon specifically to use for this purpose. I was like damn I better make sure I have a crossover cable. Surprisingly, the usb adapters talk to each other fine with a normal, non-crossover cable? Afraid this won't be the case with the internet appliance that I am *really* intending to hook up once I verify connection works with the mac.
Nov 18, 2022 at 7:34pmWeb
Show threadmccNov 18, 2022

Another update: Although the mac talks fine over a normal cable, the internet appliance *cannot* talk over the normal cable. At least, it doesn't pick up DHCP where the mac DHCP'd fine.

So now I'm ... stuck, I guess. Does it actually *need* a crossover cable but the crossover cable I bought is broken? Is something altogether other wrong? Mysteries abound and everything sucks.

Show threadmccNov 18, 2022

Nightmare updates continue: In fact, the internet appliance DOES WORK, and IS getting Internet, it's just the DHCP doesn't work and I had to manually assign an IP.

...whatever!!! Good enough!!!

Show threada kilo of saucepans (rakslice)Nov 18, 2022
@mcc Do you know if the appliance is 100base-TX or older and is expected to be used normally with a switch/hub (so is MDI and would require a crossover)? https://en.wikipedia.org/wiki/Medium-dependent_interface#Ethernet
Show threaddemizeNov 18, 2022

@mcc yeah, crossover cables haven't been necessary in a while, thanks to autonegotiation

but that's a detail that's slipped under the radar for most people

Show threadJo ShieldsNov 18, 2022
@mcc The gigabit spec requires auto-crossover-detection, but embedded devices might only have 100mbit, which might or might not
Show threadpenryuNov 18, 2022
@mcc I've also noticed a lot of ethernet devices have been more permissive about working with patch vs crossover cables, and I similarly dread the day I find myself with a strict port and the wrong cable.
Show threadDerekNov 18, 2022
@mcc Modern devices shouldn't need a crossover cable anymore, they'll just detect whether you need one and do the switch themselves.
Show threadHenryk PlötzNov 18, 2022
@mcc You shouldn't (!) need a cross-over cable even with an appliance, as long as at least one side is gigabit ethernet. Gigabit adapters *must* have Auto-MDI/MDI-X.
Show threadMatthijs De SmedtNov 18, 2022
@mcc True crossover cables haven't been needed since when Gigabit ethernet was introduced. So about 20 years. The spec requires auto crossover negotiation 🥳
Show threadErinNov 18, 2022
@mcc I think crossover being an option on the network card itself got common in the late 90s or early 2000s. I remember it being noted when I was taking my networking course in high school, but they still insisted that we make crossover cables anyway so we didn't get lazy I guess
Show threadAnn EffesNov 18, 2022
@mcc
Many if not most adapters and ethernet interfaces switch internally and automatically from cross to non cross so it usually does not matter what cable you have.
Show threadMegNov 18, 2022
@mcc honestly I'm kind of surprised you even found a crossover cable for sale since most people who actually need one these days probably just roll their own.
Show threadmccNov 18, 2022
@megmac What are the chances that this isn't a crossover cable and Amazon simply mislabeled something
Show threadMegNov 18, 2022
@mcc I would say very high chance it's just a normally wired cable (or wired the "alternative" order on both ends) and crossover is just in the listing for keyword spam.
Show threadmccNov 18, 2022
@megmac That's very possible. However, in any case, the cable literally does not work.