If you have an older Realtek 8029 network interface card, you need to use the ne2k-pci kernel module. With stock kernels shipped with most distributions today this should be no problem, they usually have this module readily precompiled.
However, if you are compiling the kernel yourself, it can be tricky to find the driver among the Linux Kernel configuration options. So here it is:
Device Drivers => Network Device Support => Ethernet driver support => National Semi-conductor devices => National Semi-conductor 8390 devices => PCI NE2000 and clones supportNote: as the help of this option says, this kernel module should be used for all of the following network cards: RealTek RTL-8029, Winbond 89C940, Compex RL2000, KTI ET32P2, NetVin NV5000SC, Via 86C926, SureCom NE34, Winbond, Holtek HT80232, Holtek HT80229.