2.1 Driver modules

When a Linux kernel is created, there are several options. The driver of a NIC can be ”compiled-in”, or it can be compiled as a module. The advantages of a module are as follows:

• The kernel itself has a small footprint because the drivers are not included in the kernel.
• The kernel can be very flexible so it can be configured on different machines with different hardware configurations.

This is why most kernels are compiled with drivers as modules. When the Linux kernel starts up, there are several methods for it to understand the hardware configuration of the machine and load the proper softwware drivers. In some distributions, the modules must be loaded manually using a configuration file. In other distributions, the modules are automatically loaded based on automatic hardware detection.

Before attempting to do anything about networking, it is important to make sure the network interface card(s) (NIC(s)) is(are) supported. The verification of the loading of the proper device driver, however, can be difficult. A part of the difficulty is because of alternative methods to load device drivers.

However, regardless of how the driver is loaded, the following command should identify the network interfaces that have drivers loaded:

Note that the output is quite long, and each line is likely to wrap around. Most systems should have a lo: (loop back) and a eth0: (ethernet) interface. Some systems may have more than one eth? interfaces if there are more than one NICs.