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this client is diskless.) Enabling this option allows Linux to answer such queries. Look into running rarp for further information about this protocol.
Another security issue you will need to contend with (especially if you are attached to the Internet) is source routed frames. IP allows for a machine originating a packet to specify the exact path of a packet from source to destination. This capability is rarely useful and is often used as a method of attacking machines across the Internet. Unless you are sure of what you're doing, you should select Yes for the IP: Drop source routed frames option.
Along with these TCP/IP-centric options are a few other protocol options such as IPX and AppleTalk. If you work in a heterogeneous environment with Macintoshes and Windows/Novell-based PCs, you might want to enable these options, but doing so isn't required as long as the other machines can talk TCP/IP. The most common use of enabling AppleTalk, for example, is to be able to use AppleTalk-based printers.
If you plan to use any SCSI chains on your system, you should select either Yes or Module for all the options on the SCSI support submenu, as shown in Figure 5.5. (If you're using SCSI disks, Yes is a better option.)
The only option worth explicitly mentioning on this submenu is Verbose SCSI error reporting (kernel size +=12K), which, when enabled, gives detailed error messages in the event of a failure somewhere along the way. Although selecting this option costs some memory, it is often worthwhile when you need to debug an error condition quickly.
Because the sample system requires SCSI, select Yes for all options except SCSI CD-ROM support because you're using an IDE CD-ROM. If you are also using a SCSI CD-ROM, you might want to select the Module option because most systems access the CD-ROM infrequently.
Obviously, if you don't select Yes to SCSI in the SCSI support submenu, the SCSI low-level drivers submenu isn't relevant to you.
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Like the submenu in Network support, the list of SCSI drivers supported by Linux increases regularly. For every SCSI card you have in your system, simply tag the option either as Yes if you intend to make heavy use of it or Module if it will have occasional only use (for example, a SCSI tape drive).
After you select the driver you want, be sure to read the corresponding help. It might contain information about where to obtain current drivers and bug fixes (if any are available).
The Network device support submenu lists the drivers available for networking. This list includes the necessary drivers to control Ethernet cards, PPP connections, SLIP, Token Ring, and so on.
You must select Yes for the first option, Network device support, if you want to select any of the other options. Otherwise, checking No dims the other options.
The next option, Dummy net driver support, provides dummy network interfaces. This capability is often used for machines providing virtual domains in which each virtual interface receives its own IP address.
The last general option is for EQL support. EQL is a means by which two modems using PPP or SLIP can work together to provide double the transfer speed. Your choice for this option is based on the fact that the machine you are connecting to can also support this capability. Unless you know you will be providing this support, be sure to check No for the EQL (serial line load balancing) support option.
The remainder of the options in this submenu are for specific network interfaces. Note that some of them are questions designed to make other options available to you. For example, if you select Yes for the 3Com cards option, all the 3Com cards that are supported become available for you to select.
The ISDN subsystem submenu doesn't provide many options for ISDN users to configure. Most people should select No for the first option, ISDN support. Doing so dims the other options in the submenu.
If you do need ISDN support, begin by selecting Yes for the first option. This way, you can configure the other items on the submenu. Because of the nature of ISDN, be sure to find out whether your provider supports some of the options that Linux supports (for example, VJ-compression with synchronous PPP).
On the CD-ROM drivers submenu, you can select the option to support non-SCSI/IDE/ATAPI CD-ROM drives. As with the other lists of drivers, you need to select Yes only for the devices that you have attached to your system.
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Linux has a great deal of support for other filesystems, thereby allowing you to use disks from other systems without any conversion process. The most notable support is for the DOS-based filesystems.
As of the 2.0.30 kernel, the following filesystems on the Filesystems submenu are available for your use:
| Filesystem | Description |
| Minix | This original Linux filesystem is still used by boot disks and common floppy disks. This option should be tagged Yes. |
| Extended fs | This first successor to the Minix is no longer used. There is no good reason to enable support for this filesystem. |
| Second extended fs | This is the current default Linux filesystem. You should definitely select Yes for this option. Remember: Your root filesystem cannot be a module. |
| xiafs filesystem | This filesystem was introduced at the same time as the Second extended fs as a replacement for the Extended fs; however, it never really caught on and is rarely used today. Unless you have a specific need, you should select No for this option. |
| DOS FAT fs | This particular option isn't a filesystem but a foundation for other FAT-based filesystems such as MS-DOS FAT, VFAT (Windows 95), and umsdos support. |
| MS-DOS FAT fs | If you want to be able to access DOS-based systems from Linux, you need to set this option to Yes. This capability is especially useful for dual boot systems. |
| VFAT (Windows 95) fs | VFAT is the upgrade from the original MS-DOS FAT structure; it includes support for long filenames. Again, if you are in a dual boot situation, having this capability is a good idea. |
| umsdos | This UNIX-like filesystem resides on top of the standard MS-DOS format. This capability is useful if you want to run Linux over your DOS partition occasionally. For a serious system, you should not need this support. (Red Hat Linux does not support running on a umsdos filesystem.) |
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