UNIX System Administration Handbook - Evi Nemeth [497]
tftpd: trivial file transfer server
tftpd implements a file transfer protocol similar to that of ftpd, but much, much simpler. Many diskless systems use TFTP to download their kernels from a server. tftpd does not perform authentication, but it is normally restricted to serving the files in a single directory (usually /tftpboot). Since anything placed in the TFTP directory is accessible to the entire network, it should contain only boot files and should not be publicly writable.
rarpd: map Ethernet addresses to IP addresses
rarpd implements RARP, the Reverse Address Resolution Protocol. This mostly abandoned protocol allows diskless machines to determine their IP addresses at boot time. rarpd runs on a server; one copy is generally started at boot time for each network interface that needs RARP support. rarpd uses the /etc/ethers and /etc/hosts files to determine appropriate mappings, so there is no need for a separate configuration file. RARP is a subset of BOOTP, but your hardware will dictate which protocol you must use (possibly both).
bootparamd: advanced diskless life support
bootparamd uses the /etc/bootparams file to tell diskless clients where to find their filesystems. bootparamd service is often used by machines that get their IP addresses by using RARP and that use NFS to mount their filesystems.
dhcpd: dynamic address assignment
The Dynamic Host Configuration Protocol (DHCP) provides PCs, laptops, and other “mobile” platforms with information about their IP address, default gateway, and name server at boot time. dhcpd is the daemon that implements this service under UNIX. You can find more information about DCHP on page 287.
2. Solaris is an exception to this behavior. See page 109 for the sordid details.
3. Port numbers are not arbitrary. All machines must agree about which services go with which ports; otherwise, requests will constantly be directed to the wrong port. If you are creating a site-specific service, pick a high port number (in the thousands) that is not already listed in the services file.
4. Actually, sync simply schedules these blocks to be written out; it doesn’t guarantee that writing has completed by the time it returns.
5. The rpc prefix, when present, is just there to remind you that the daemon uses RPC.
6. The official explanation is that biff stands for “bark if from found.” Biff was actually the name of Heidi Stettner’s dog, who always barked when the mailman came.
7. The rsh command is called remsh on HP-UX.
8. adjtime biases the speed of the system’s clock so that it gradually falls into correct alignment. When the system time matches the current objective time, the bias is cancelled and the clock runs normally.
Colophon
We produced the first edition of this book with the UNIX troff package. For the second edition, we used a Macintosh. We produced this third edition entirely on Microsoft Windows 95, 98, and 2000. Oh, such delight! We’ll never touch UNIX again.
We used Adobe FrameMaker for layout, with Adobe Illustrator and Adobe Photoshop for graphics and illustrations. We also used Adobe Acrobat throughout the production process. It allowed us to distribute chapters and graphic files to many different people without worrying about fonts or application compatibility. We delivered the final manuscript as an Acrobat file, too.
Tyler Curtain drew the cartoons using pen and ink. We scanned them on a desktop scanner, cleaned them up in Photoshop, and converted them to PostScript artwork with Adobe Streamline.
The body text is Minion Multiple Master, designed by Robert Slimbach. Headings, tables, and illustrations