As you learned in the last chapter, a computer can have multiple Ethernet cards (interfaces), and each of these cards can have multiple IP addresses and related settings. The convention is for each machine to have one Ethernet card with one IP address, but there's no reason to limit yourself in that regard. This chapter shows you how to set up as many simultaneously installed cards as you like. You also learn how to bind as many IP addresses to each card as you see fit. The first step is to make sure you have at least one Ethernet card that FreeBSD will work with. Table 23.1 lists all the cards (more specifically, chipsetscards from different manufacturers often use standardized chipsets that FreeBSD recognizes) that are supported in the GENERIC kernel. These cards comprise the vast majority of those used today, and your system should recognize any of these without any additional tweaking. The PCI cards are particularly well recognized by FreeBSD. A good many other cards are supported by FreeBSD but not included in the GENERIC kernel; drivers for these cards are usually available as kernel modules that are automatically loaded at boot time if necessary. For example, the an driver (for the Aironet Wi-Fi chipset) is available as /boot/kernel/if_an.ko. Refer to /sys/conf/NOTES (as discussed in the section "The NOTES Files and LINT," in Chapter 18, "Kernel Configuration") and recompile the kernel to include support for your card if you want to improve your system's boot time and stability by avoiding loading kernel modules.
Note Be aware that the list of supported Ethernet cards changes fairly frequently. The devices are listed in the GENERIC kernel config file on your system, /sys/i386/conf/GENERIC. This will be the authoritative source for what cards are supported by your system. Most Ethernet cards sold today for x86 hardware are PCI-based. This means that the PCI controller handles all the addressing automatically and you don't need to do any of the IRQ/DMA/memory address gyrations associated with ISA cards, the last of which was seen in the late 1990s. If you're stuck with one of these older cards, though, there are a few things you need to do, such as setting the card's memory address and IRQ through a DOS utility and modifying the device hints for the card. You learn more about these accommodations in the sidebar "Coping with ISA Ethernet Cards" later in this chapter. |