Setting primary interface in ubuntu

Unlike CentOS, ubuntu doesn’t provide a nice tool to set default routes when there are more than 1 ethernet interfaces are connected at the same time. It is possible to set up a static route with post-up but it is still difficult to do if the DHCP range is dynamic and you can’t accurately determine the proper gateway.

I was able to reliably implement it with the following settings.
Open /etc/network/interfaces file and
Add the following line to all other interfaces that does NOT act as a default gateway.

post-up route del default dev $IFACE

This code, instead of setting a default route, basically removes undesired default routes as the device goes up.

Example configuration when you want to use ens160 as default route:

auto ens172
iface ens172 inet dhcp
post-up route del default dev $IFACE

auto ens192
iface ens192 inet dhcp
post-up route del default dev $IFACE

# The primary network interface
auto ens160
iface ens160 inet dhcp

Converting Killer LAN / WLAN cards to Atheros cards

If you feel frustrated by buggy drivers and softwares of Killer ethernet cards that come with your new gaming laptop or motherboard, it is possible to get rid of them by force replacing the drivers. I experienced continuous disconnection while creating a testnet with this card and it was unacceptable. I honestly have no idea why manufacturers even use this chipset even though people were complaining about this for a long time.

Killer chipsets are basically rebranded versions of existing Atheros chipsets, so  you can simply override the default driver settings to make it function as an Atheros card.

 

1. Open the device manager
2018-11-23 02_07_04-Device Manager

 

2. Right click on the LAN card and choose to update driver software
2018-11-23 02_07_50-NVIDIA GeForce Overlay

3. Browse my computer for drivers
2018-11-23 02_08_11-Update Driver Software - Killer E2400 Gigabit Ethernet Controller

4. Pick from a list on my computer
2018-11-23 02_08_45-Update Driver Software - Killer E2400 Gigabit Ethernet Controller

5. Have driver disk
2018-11-23 02_09_04-Update Driver Software - Killer E2400 Gigabit Ethernet Controller

6. Choose the appropriate inf file for your device. There is a list of compatible drivers at the end of this article
2018-11-23 02_09_43-Device Manager

7. If the inf file contains multiple definitions, choose the appropriate model
2018-11-23 02_10_04-Update Driver Software - Killer E2400 Gigabit Ethernet Controller

8. Ignore the warning and proceed
2018-11-23 02_10_15-Update Driver Warning

9.You have a functional Atheros card now, goodbye retarded Killer drivers
2018-11-18 13_13_00-Device Manager

10. Remove the Killer suite from Add/Remove Programs if you installed them

 

List of compatible drivers:

Killer E2200 – Atheros AR8151
Killer E2400 – Atheros AR8171

Killer Wireless 1535 – Qualcomm QCA61x4A

 

Please tell me if you know any other compatible pairs, I’ll add them to this list.