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  Thin Client: New User Guide
  Stephen Noble stephen7 at bigfoot.com
  30th November 1999

  1.How to turn inexpensive legacy computers into fast terminals using
  the power of your main computer, you will need : A fast computer to
  act as Server, A client computer (old and unwanted). Linux compatible
  network cards. A connection between computers.  2.How to centralise
  system administaration by useing NFS, ie placing the entire file sys-
  tem of a faster client on the server.
  ______________________________________________________________________

  Table of Contents


  1. Introduction

  2. Hardware and Documentation

     2.1 Hardware
     2.2 Documentation

  3. Server setup

     3.1 Check your network services on your server
     3.2 Setting up a dhcpd daemon
     3.3 Tftpd setup
     3.4 Kernel image
     3.5 Security

  4. Client setup

  5. Network files system

     5.1 server specific
     5.2 client specific

  6. X-terminal

  7. Acknowledgments & further exercises



  ______________________________________________________________________

  1.  Introduction


  o  Linux allows any reasonably new computer to be used as a server to
     a thin client, or many thin clients, these thin clients can be
     inexpensive legacy computers. For a console terminal you need a 386
     with 4-8mb of ram, or for an X-Terminal a 486/66 with 8-16mb ram.

  o  One Option is without a hard drive, it keeps the noise down and
     simplifies administration as you only have one system to maintain.

  o  If you have legacy apps, you can have them on a hard drive with
     it's legacy Operating System

  o  This howto is aimed at those new to Unix/Linux, it will cover the
     essential areas you need to be aware of and point you to other
     documentation in that area you need to be familiar with.

  o  You will probably use this as an aid to the
     http://www.slug.org.au/etherboot/  documentation, I include some
     more examples of config files, and leave many of the other features
     of etherboot as an exercise for the reader

  o  If your client is sufficiently powerful only the file system need
     be shared, applications can run on the client system. (say a 233
     32mb ram).  Install an application on the server and all clients
     have access



  2.  Hardware and Documentation


  2.1.  Hardware

  When you start, you will need at least this



  o  a computer to act as Server,

  o  a client computer, I unplugged the power to the hard disk and
     disabled the drive in the bios to emulate a diskless machine

  o  compatible network cards

  o  connection between computers, I used twisted pair ethernet with
     RJ45 terminators

  o  For two computers a cross-over cable  is sufficient, and saves
     another power point, the first computer shop I went to gave me
     blank stares, idiots !

  o  For two or more clients, you need a hub, a kit with a 10 mb 4 port
     hub ,2 cards sells for under A$150, you can probably do better,
     I've had some success with $5 second hand cards, 3m cables for $6,
     a new hub for $40, a found monitor and a $60 pentium 75


  2.2.  Documentation

  You may like to familiarise yourself with the linux documentation,
  specifically you can read (skim) for an overview the following :


  o  /usr/doc/HOWTO/mini/Diskless - a similar howto tackling this
     problem

  o  Networking Overview HOWTO - Networking capabilities of the Linux

  o  Ethernet HOWTO -  Information on Ethernet hardware compatibility

  o  NET-3 HOWTO -  How to configure TCP/IP networking under Linux.


  Also you probably have in the  /usr/doc/LDP/ directory

  o  The System Administrators' Guide

  o  The Network Administrators' Guide

  o  Linux Installation and Getting Started


  The obligitory link


  o  http://www.magma.ca/~bklimas help for new linux users.


  One last thing

  o  my network server is snoball , my client is elite and my
     (local)domain is gundog.net Replace with your computers names where
     applicable


  3.  Server setup

  The server needs to be setup in readiness for the client in a number
  of ways


  3.1.  Check your network services on your server

  run the command /sbin/ifconfig if your output is similar to below then
  your loopback and ethernet card are correctly configured.


  ______________________________________________________________________
  [cassie@snoball cassie]$ /sbin/ifconfig
  lo        Link encap:Local Loopback
       inet addr:127.0.0.1  Bcast:127.255.255.255  Mask:255.0.0.0
       UP BROADCAST LOOPBACK RUNNING  MTU:3584  Metric:1
       RX packets:854 errors:0 dropped:0 overruns:0 frame:0
       TX packets:854 errors:0 dropped:0 overruns:0 carrier:0
       collisions:0
  eth0      Link encap:Ethernet  HWaddr 00:AA:00:BB:BD:09
       inet addr:192.168.53.1  Bcast:192.168.53.255  Mask:255.255.255.0
       UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
       RX packets:190369 errors:0 dropped:0 overruns:0 frame:0
       TX packets:249267 errors:0 dropped:0 overruns:0 carrier:1
       collisions:4793           Interrupt:5 Base address:0x320
  ______________________________________________________________________



  If not ...

  o  loopback, if this isn't here you need to activate it at start up,

  o  ethernet card, is it being detected,is the driver a module

  o  you can set these in linuxconf or netcfg


  3.2.  Setting up a dhcpd daemon

  Here the server gives out IP numbers to requests by clients


  o  is DHCPD installed, maybe (as root) just run ntsysv and have it
     start at boot time

  o  this /etc/dhcpd.conf file assigns static IP numbers if you have a
     matching MAC address, A MAC address is a unique 'number' given to
     the NIC.  The start of the 'number' is based on the manufacturer,
     if you don't have a sticker on the card, attempt to load the rom
     image from eprom or floppy and see what it reports. (see client
     setup)


     ___________________________________________________________________
     #/etc/dhcpd.conf
     subnet 192.168.35.0 netmask 255.255.255.0 {
         option domain-name "gundog.net";
         range dynamic-bootp 192.168.35.128 192.168.35.255;
         default-lease-time 21600;
         max-lease-time 43200;
         }

     host 286 {
             filename "/tftpboot/kermit.nb";
             hardware ethernet 00:80:c8:22:ae:de;
             fixed-address 192.168.35.70;
             }

     host elite {
         filename "/tftpboot/vmlinuz.xterm";
         hardware ethernet 00:00:79:80:34:c9;
         fixed-address 192.168.35.23;
             option host-name "elite";
     ___________________________________________________________________



  o  the /etc/hosts file resolves IP numbers into host names

     ___________________________________________________________________
     #etc/hosts
     127.0.0.1       localhost    localhost.localdomain
     192.168.53.1    snoball      snoball.gundog.net
     192.168.53.23   elite        elite.gundog.net
     ___________________________________________________________________



  3.3.  Tftpd setup

  trivial ftp - after you have your IP number your client requests a
  kernal, this is delivered over ethernet.

  o  Install tftpd, make sure it's active in /etc/inetd.conf, typical
     line


     ___________________________________________________________________
     tftp dgram udp wait root /usr/sbin/tcpd in.tftpd -s /tftpboot
     ___________________________________________________________________



  restart inetd, kill -HUP "process id of inetd"


  3.4.  Kernel image

  You must compile a kernel for the Client that includes NFS support and
  the NIC driver for that client compiled in (not modules).  Answer yes
  to Root file system on NFS? and BOOTP support?

  After building the kernel, run mknbi-linux from the Etherboot
  distribution on it.(the mknbi program in the netboot/linux directory)
  Install this tagged image as /tftpdir/"vmlinuz.xterm".


  see etherboot-4.2/doc/html/README-3.html

  should i put a copy of mine somewhere for download RH6.0 ne2000 NIC


  3.5.  Security

  It's easiest to allow anybody and anything to run services and process
  on your computer, but one day you will be sorry. You restrict these by
  your /etc/hosts.deny and specifically restore rights by
  /etc/hosts.allow, indicative examples :

  ______________________________________________________________________
  #hosts.deny
  # all except those in hosts.allow
  ALL:ALL


  #hosts.allow
  #only hosts within my domain and my host at home.
  ALL:LOCAL, 192.168.53.       #<-- note:no space after :
  ______________________________________________________________________



  more security - look for more information in the ldp-howto's and if
  your using etherboot, in it's security howto.


  4.  Client setup

  Network loader

  A small program that runs as a BIOS extension, can be loaded from a
  floppy, or you can burn an eprom chip and insert it on your network
  card for a totally diskless client. It handles the DHCPD query and
  TFTP loading and then transfers control to the loaded image. It uses
  TCP/IP protocols.


  There are two free implementations of TCP/IP net loaders: Etherboot
  and Netboot: Etherboot uses built-in drivers while Netboot uses Packet
  drivers.


  o  see etherboot-4.2/doc/html/README-2.html,

  o  I compiled the option to ask local or Network and default to local
     after 5 seconds

  o  making a boot rom floppy, floppyload.bin was tricky to find, I
     copied it into the directory of compiled rom images

     ___________________________________________________________________
     cat floppyload.bin ne2000.lzrom > /dev/fd0
     ___________________________________________________________________



  5.  Network files system


  The Client requests to mount /tftpboot/<IP address of client> as its /
  by NFS from server. You must export this from the server,(maybe
  symlink to /tftpboot/client to be safe.)

  NFS is a big topic there is a HOWTO and two mini Howto's.

  first you need to create a copy of your current system under /tftpboot
  ken has written two scripts that do all your work, I called them
  makefirst and makecopy. my first client takes 20-30mb and the copy
  less. I used du -h to look for large unnecesary files.

  see etherboot-4.2/doc/html/diskless-5.html

  the following seem to me to be the critical files here


  5.1.  server specific


  ______________________________________________________________________
  #/etc/exports
  /tftpboot/elite             elite(rw,no_root_squash)
  /tftpboot/elite             gordon(rw,no_root_squash)
  /usr                        *.gundog.net(ro)
  /home                       *.gundog.net(rw)
  /mnt/cdrom                  (ro)

  run exportfs -a  to reread the exports file after
  changes /usr/sbin/exportfs --help


  #/etc/sysconfig/network
  NETWORKING=yes
  FORWARD_IPV4="no"
  HOSTNAME="snoball"         <-----------
  GATEWAYDEV=""
  GATEWAY=""


  #/etc/sysconfig/network-scripts/ifcfg-eth0
  IPADDR="192.168.53.1"            <-----------
  BOOTPROTO=none
  ______________________________________________________________________



  5.2.  client specific



  ______________________________________________________________________
  #tftpboot/elite/etc/fstab
  snoball:/tftpboot/elite    /               nfs rw  1 1
  none                    /proc proc          defaults   0 0
  snoball:/usr           /usr                 nfs     ro  1 1
  snoball:/home          /home                nfs     rw  1 1


  #tftpboot/elite/etc/sysconfig/network
  NETWORKING=yes
  FORWARD_IPV4=nomore
  HOSTNAME=elite
  GATEWAYDEV=
  GATEWAY="192.168.53.1"       <-----------


  #/tftpboot/elite/etc/sysconfig/network-scripts/ifcfg-eth0
  DEVICE=eth0
  USERCTL=yes
  ONBOOT=yes
  BOOTPROTO=none
  BROADCAST=192.168.53.255
  NETWORK=192.168.53.0
  NETMASK=255.255.255.0
  IPADDR=192.168.53.23         <-----------
  ______________________________________________________________________



  #odd fiddles #itemize> #item>fast...  #item>cp /usr/bin/xargs
  /tftpboot/client/bin/xargs #/itemize>


  6.  X-terminal


  With no further changes your client should boot on the CLIENT pc, it
  just happens to be sharing it's files via NFS

  At this point you have a console terminal. you need to make just a few
  more changes to run X



  o  Configuring X

     As root on client run Xconfigurator and mouseconfig,

     If this fails use XF86Setup check your RPMS dir on your CD (eg.ls
     *Setup*)


  o  X Font Server



     ___________________________________________________________________
     #chech how xfs starts on server /etc/rc.d/init.d/xfs
       start)
         echo -n "Starting X Font Server: "
         rm -fr /tmp/.font-unix
         daemon --check xfs su xfs -c xfs -s /bin/sh
         touch /var/lock/subsys/xfs
         echo
         ;;

     #edit XF86Config for all machines
         FontPath  "tcp/snoball:7100"
     ___________________________________________________________________



  o  Console login

     You are now set up for a console login to the client PC. You are
     using the client memory and processor, this is adequate for console
     programs and there and many or great merit, program in python,
     email with pine or browse with lynx.


     You may still start X from here, make the server changes in the
     next section, at the prompt type X -query snoball and you will get
     the login box to the server


  o  Graphical login

     Server set up


     ___________________________________________________________________
     1. Make sure the client is matched by a clause in /etc/X11/xdm/Xaccess
     *   CHOOSER BROADCAST   #any indirect host can get a chooser


     2. Comment out the :0 in /etc/X11/xdm/Xservers
     #:0 local /usr/X11R6/bin/X

     3. Then make sure that xdm is run from the init scripts.
     #etc/inittab
     id:5:initdefault:

     and
     # Run xdm in runlevel 5
     # xdm is now a separate service
     x:5:respawn:/etc/X11/prefdm -nodaemon
     xdm:5:respawn:/usr/X11R6/bin/xdm -nodaemon
     ___________________________________________________________________



  On the client

  Get the slow PC's to run on the server, Fast PC's (eg 166mhz 32mb
  ram)can run ok on their own CPU and memory


  the part maarked WARNING dosn't actually work as yet, but I'm close to
  getting the syntax correct, use the two stage method via the console
  login in the mean time.

  ______________________________________________________________________
  #/tftpboot/elite/etc/inittab

  id:5:initdefault:                                    #WARNING
  x:5:respawn:/usr/X11R6/bin/Xwrapper -query snoball   #WARNING

  OR to run on client ??

  id:3:initdefault:                                    #runlevel 3 ie console
  x:5:respawn:/etc/X11/prefdm -nodaemon
  ______________________________________________________________________



  7.  Acknowledgments & further exercises


  Markus Gutschke and Ken Yap the authors of the Etherboot program.



  Extend your system with the following programs

  o  squid -      cache your web browsing for others on your network

  o  junkbuster - banish web banner adds

  o  mailman -    mailinglist ;setup via e-mail or web

  o  imp -        web based email (with a java enabled browser)

  o  python -     for some Java and C is just too hard

  o  sgmltools -  knock out multiple versions of your docs

  o  suggestions ?

  stephen7 at bigfoot.com







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