Debian 9 - Install Realtek Firmware

Perform the steps below if you ever see the following message in Debian 9:

Possible missing firmware /lib/firmware/rtl_nic/rtl8168d-1.fw for module r8169

Steps

Update Sources

Add the following line to the end of your /etc/apt/sources.list file:

deb http://httpredir.debian.org/debian/ stretch main contrib non-free

Optional: For those lazy like me, you can perform the step above with this in one CLI command:

sudo echo "deb http://httpredir.debian.org/debian/ stretch main contrib non-free" | \
  sudo tee -a /etc/apt/sources.list

Update your package cache for the previous change to take effect so that you have access to the firmware-realtek package, and then install it.

sudo apt update \
  && sudo apt-get install firmware-realtek

References

• Ask Ubuntu - Possible missing firmware /lib/firmware/rtl_nic/rtl8105e-1.fw for module r8169 with 2.6.39 kernel
• Debian Wiki - rtl819x