HP World Linux Network Install Hands On. Rob Lucke

Transcription

1 HP World 2004 Linux Network Install Hands On Rob Lucke

2 Seminar Agenda (part 1) Introduction 1. Network Installation Why network installation? Network booting basics Linux system start-up Network booting start-up Initial RAM disks 2. Network Booting Infrastructure DHCP TFTP pxelinux Linux kernel and initial RAM disk (initrd) image Lab 1: DHCP, TFTP, pxelinux, and the Linux initrd

3 Seminar Agenda (part 2) 3. Network Installation Types Manual with anaconda Automated Red Hat kickstart Automated image installation with SystemImager Lab 2: Network Installations 4. Multicast Installation SystemImager s flamethrower facility Lab 3: Multicast SystemImager flamethrower Installations 5. Summary 6. Questions and Test-driving

4 Introduction: About this Session The Linux distribution being used for this session is Red Hat Fedora Core 2 Installation software being used is: pxelinux (version 2.1) info on download DHCP TFTP (hpa version 0.37) SystemImager and flamethrower (version 3.2.0)

5 Setting Some Expectations Note! This seminar is intended to teach you about things that are very dependent on network and system hardware configurations. At the time this seminar was written, the lab hardware configuration was unknown. The instructor will do his best to stick to the written material, but some things are out of his hands.

6 Section 1: Network Installation Overview

7 Why Network Installation? One location for the software on multiple machines Flexibility to support multiple distributions or configurations Minimal manual intervention needed No floppies, CD-ROMs, or DVDs involved You need not be present to win Users can be taught to install their own machines No local volatile data, nothing to lose Don t troubleshoot, just reboot Fails once, reinstall Fails twice, replace the hardware It is just plain easier once the infrastructure installation overhead is recouped

8 System Management Model for Machine Classes

9 Linux Disk-based Booting Process Hardware power-on self test (POST) Boot device selection (user input or default) Load the boot sector Execute the bootloader Select kernel configuration to boot (manual or default) Kernel version and parameters passed to it Initial RAM disk image Bootloader loads kernel and initrd into memory Bootloader executes kernel Kernel mounts initrd and executes start-up script Kernel moves root file system to the disk device Kernel executes init The init process runs the system startup scripts specified in the /etc/inittab file

10 The GRand Unified Bootloader, GRUB Time Interactive Interactive PC BIOS GRUB stage1 (stage1 fs support) GRUB stage2 Linux Kernel Boot Sector (MBR) Loaded from the /boot/grub directory Initial RAM disk Image grub.conf is loaded from the /boot/grub directory

11 Example GRUB Configuration File # grub.conf generated by anaconda # # Note that you do not have to rerun grub after making changes to this file # NOTICE: You have a /boot partition. This means that # all kernel and initrd paths are relative to /boot/, eg. #boot=/dev/sda default=2 timeout=10 splashimage=(hd0,2)/grub/splash.xpm.gz title Red Hat Linux ( smp) root (hd0,2) kernel /vmlinuz smp ro root=label=/ hda=ide-scsi hdb=ide-scsi initrd /initrd smp.img title WindowsXP rootnoverify (hd0,0) chainloader +1

12 Kernel Parameter Passing The Linux kernel may be passed parameters like any other program Linux kernel parameters are documented in /usr/src/linux-<version>/documentation/kernel-parameters.txt, if you have the kernel-source package loaded Parameters that are passed to the kernel may be removed from the command line if the kernel understands them Kernel modules have access to the kernel command line Parameters that are not removed are available to the init process and also inside of the start-up script in the initrd (this is very useful!)

13 Useful Boot-time Parameters root=<device> root=/dev/sda2 nfsroot=<directory> nfsroot=/sharedroot nfsaddr=<ip-address> nfsaddr= init=<program> init=mystartup initrd=<ramdisk> initrd=netboot/initrd load_ramdisk=<1 or 0> load_ramdisk=1 mem=<n k,m,g> mem=128k ramdisk_size=<n KB> ramdisksize=4096 (default) ro rw console=<dev>[speed,control,parity] console=/dev/ttys0,9600,n,8 vga=<mode> vga=788 See /usr/src/linux-<version>/documentation/svga.txt

14 Network Boot Sequence Hardware power-on self test (POST) PXE or DHCP boot device selected (manual or default) The boot firmware broadcasts the network boot request with the primary interface s MAC address Remember that network broadcast frames are limited to the local LAN segment (or switch domain), but there are helper programs available to extend that reach The DHCP or PXE server answers request with IP address information and file name PXE firmware downloads boot file via TFTP PXE firmware executes file at a known location Boot file continues, either executing or continuing to load additional files File loaded by PXE may be: Kernel Network boot loader like pxelinux

15 The Initial RAM Disk Image, initrd An initrd is a compressed file system that usually contains the minimal set of modules necessary to mount the root device, along with a simple startup script This approach is necessary because the dynamically loaded modules necessary to mount the device actually may be on the device to be mounted (Can you say chicken or egg? ) The file system in the initrd is frequently a Linux ext2 file system, but can also be something like cramfs The Linux kernel can decompress the file, which is available from a special device, to RAM and mount it as a (usually) temporary root file system Once mounted, the start-up script is executed

16 An Example linuxrc Script from Fedora s initrd #!/bin/nash mount -t proc /proc /proc setquiet echo Mounted /proc filesystem echo Mounting sysfs mount -t sysfs none /sys echo "Loading scsi_mod.ko module" insmod /lib/scsi_mod.ko echo "Loading sd_mod.ko module" insmod /lib/sd_mod.ko echo "Loading aic7xxx.ko module" insmod /lib/aic7xxx.ko echo "Loading raid1.ko module" insmod /lib/raid1.ko echo "Loading jbd.ko module" insmod /lib/jbd.ko echo "Loading ext3.ko module" insmod /lib/ext3.ko raidautorun /dev/md0 raidautorun /dev/md1 raidautorun /dev/md2 echo Creating block devices mkdevices /dev echo Creating root device mkrootdev /dev/root umount /sys echo 0x0100 > /proc/sys/kernel/real-root-dev echo Mounting root filesystem mount -o defaults --ro -t ext3 /dev/root /sysroot pivot_root /sysroot /sysroot/initrd umount /initrd/proc

17 Unpacking and Repacking an initrd File # cd /tmp # mkdir image # gunzip < /boot/initrd-<version>.img > myinitrd # losetup /dev/loop0 myinitrd # mount o loop /dev/loop0 image # cd image # umount image # losetup d /dev/loop0 # mount o loop myinitrd image # cd image # umount image Option 1 All of the details Option 2 Just make it easy # gzip -9 < myinitrd > mynewinitrd

18 Section 2: Network Installation Infrastructure

19 The Network Boot Sequence with pxelinux and DHCP

20 Configuring Linux DHCP Services The DHCP server can be a big help to you as a system manager. It can fill in lots of client configuration information for you You can specify default parameters to all client systems serviced by the DHCP server The server configuration file is /etc/dhcpd.conf The DHCP client (dhcpcd) will fill in all of the information in configuration files on the system at boot time To see the client information for DHCP, look at the /var/lib/dhcp/dhclient-eth0.leases file See man pages for dhcp.conf, dhcp.leases, dhcp-options, and dhclient.conf

21 Setting Up the DHCP Server, dhcpd Make sure you installed the DHCP server rpm file Create the /etc/dhcpd.conf file Execute chkconfig dhcpd on to create startup links Execute service dhcpd start to start the server Check the /var/log/messages file for DHCP server logging messages Edit the /etc/dhcpd.conf file as necessary Execute service dhcpd restart to stop and restart the DHCP server Note that /etc/sysconfig/dhcpd contains a variable definition, DHCPDARGS, that is sourced by the startup this is useful for setting options: DHCPDARGS= eth0 Note: There is a DHCP protcol relay agent dhcrelay that can forward DHCP requests from a subnet to a server with no direct connection, see man dhcrelay for information

22 Example DHCP Configuration File ddns-update-style none; default-lease-time ; use-host-decl-names = true; boot-unknown-clients = true; authoritative; # include "/etc/dhcpd.failover"; # # shared-network home { subnet netmask { option domain-name-servers , ; option domain-name "lucke.home"; option netbios-name-servers ; option log-servers ; option nis-domain "home.lucke"; option nis-servers , ; option ntp-servers , ; option routers ; option subnet-mask ; option broadcast-address ; DHCP can update dynamic DNS if you have that service. It will register the host and IP information into the DNS server. If you have another DHCP server in your network, make sure to set non-authoritative or you will NAK the requests of other systems and your IT guys will not like you any more. Default options sent to all DHCP clients for the subnet.

23 Example DHCP Configuration File (continued 1) group physical-hosts { host hpvpw1 { option host-name "hpvpw1"; hardware ethernet 00:0E:0C:2E:3B:46; fixed-address ; } } host hpvpw2 { option host-name "hpvpw2"; hardware ethernet 00:60:B0:FC:51:31; fixed-address ; } host hplj2300 { option host-name "hplj2300"; hardware ethernet 00:01:E6:AA:90:F1; fixed-address ; } # Netgear ME-102 wireless access point host ngme102 { option host-name "ngme102"; hardware ethernet 00:09:5B:39:E6:79; fixed-address ; } Entry specifying hostname, MAC address, and IP address for one system

24 Booting with DHCP group PXE-clients { allow booting; allow bootp; next-server ; # TFTP server filename "pxelinux.0"; # Relative to /tftpboot! host nec1 { option host-name "nec1"; hardware ethernet 00:20:78:11:3C:F1; fixed-address ; } host hpepc1 { option host-name "hpepc1"; hardware ethernet 00:01:02:03:EB:9B; fixed-address ; } Entry specifying hostname, MAC address, and IP address for one system host hpxw4100 { option host-name "hpxw4100"; hardware ethernet 00:30:6e:4c:34:4e; fixed-address ; } }

25 Example DHCP Client Information From /var/lib/dhcp/dhclient-eth0.leases: lease { interface "eth0"; fixed-address ; option subnet-mask ; option routers ; option dhcp-lease-time 86400; option dhcp-message-type 5; option domain-name-servers ; option dhcp-server-identifier ; option nis-domain "home.domain"; option nis-servers ; option ntp-servers ; option broadcast-address ; option domain-name "dsl-verizon.net"; renew /7/4 01:29:59; rebind /7/4 11:33:53; expire /7/4 14:33:53; } Default information passed from the DHCP server Note that the DHCP server identified itself in the reply to the client s broadcast

26 DHCP Subsystem Overview

27 Building and Installing the TFTP Software Download the package tftp-hpa-0.36.tar.gz # tar xvzf tftp-hpa-0.36.tar.gz # cd tftp-hpa-0.36 #./configure # make # make install This installs the in.tftpd daemon and the tftp client software The TFTP service is started by xinetd Be aware that TFTP is a possible security hole unless you set the chroot behavior to limit file system access

28 Configuring the TFTP Service /etc/xinetd.d/tftp service tftp { socket_type = dgram protocol = udp wait = yes user = root server = /usr/sbin/in.tftpd server_args = -s /tftpboot -v disable = no per_source = 11 cps = flags = IPv4 } Limit access to the /tftpboot directory, and set the verbose logging option for debugging purposes The next step is to restart the xinetd service with service xinetd restart to enable the tftp server

29 What s in the /tftpboot Directory? First, the pxelinux.0 file is the network bootloader that is delivered by tftp (more on the other files later) Next, the boot kernels and initial RAM disk images. Also, there is the configuration data for pxelinux

30 The pxelinux Files: default.netboot # Remember everything is relative to /tftpboot! # default local # Uninterrupted network boot does this label serial 0,38400n8 # Serial port at Baud 8 bits not parity 1 stop bit prompt 0 # Will stop if Shift-Ctrl held or <Caps Lock> or <Scroll Lock> enabled F1 help.txt # Will display help if a function key is pressed at the boot: prompt label fedora.ksc1 kernel FkC1/vmlinuz append vga=extended load_ramdisk=1 initrd=fkc1/initrd.img ks=nfs: :/kickstart/ks.fc1/ label fedora.c2in kernel RfC2/vmlinuz append vga=extended load_ramdisk=1 initrd=rfc2/initrd.img label image.si kernel Si/kernel append vga=extended load_ramdisk=1 prompt_ramdisk=0 initrd=si/initrd.img root=/dev/ram rw \ ramdisk_blocksize=4096 label local localboot 0

31 The pxelinux Files: Help File /tftpboot/help.txt 79 Available options for the boot are: redhat.ks72 Do an automatic kickstart installation of Red Hat 7.2 redhat.ks73 Do an automatic kickstart installation of Red Hat 7.3 redhat.ks80 Do an automatic kickstart installation of Red Hat 8.0 redhat.ks90 Do an automatic kickstart installation of Red Hat 9.0 fedora.ksc1 Do a manual Red Hat Fedora Core 1 installation fedora.ksc2 Do a manual Red Hat Fedora Core 2 installation This file is made available by the pxelinux command line when the proper function key is pressed redhat.72in Do a manual Red Hat 7.2 installation redhat.73in Do a manual Red Hat 7.3 installation redhat.80in Do a manual Red Hat 8.0 installation redhat.90in Do a manual Red Hat 9.0 installation fedora.c1in Do a manual Red Hat Fedora Core 1 installation fedora.c2in Do a manual Red Hat Fedora Core 2 installation image.si Do a system imager installation local Boot from local disk Enter a selection to continue the boot process. 09

32 Specifying pxelinux Client Boot Behavior #!/bin/bash -x SCRIPT="default.netboot" if [ -n "${1}" ]; then SCRIPT="${1}" fi for HEXIP in $( sed 's@#.*$@@' < IPS.hex ) do [[ -f "${HEXIP}" ]] && continue ln -s "${SCRIPT}" "${HEXIP}" done I use a small, very simple script to create links for all of the client IP addresses to the default.netboot script. It is also possible to create links for the MAC addresses in a similar fashion: 00-0c-29-dc-1b-a5 00-0e-0c-2e-3b-46 C0A80065 # nec1 C0A80067 # hppav1 C0A8006D # hpepc1 C0A8006E # nec2 C0A8006F # hpxw4100 C0A80071 # hpxw8000 C0A800BC # vmlinfc02

33 The pxelinux Configuration File Search pxelinux will look in the base /tftpboot directory for the the pxelinux.cfg directory If a match is found for the client MAC address in the pxelinux.cfg directory, that configuration file is used If the MAC address is not found, pxelinux searches for the hexidecimal IP address for the client If the full hex IP address for a client is not found, then one hex digit is removed and the search is repeated until no digits are left If no IP address is found, then pxelinux will to use the file default for configuration If no match is found, pxelinux will wait for 5 minutes and then retry the process It is a real good idea to use the default file as a catch-all, so that it only does a boot from the local disk Example: Try MAC: 00-0e-0c-2e-3b-46 Try C0A > C0A8006 -> C0A800 -> C0A80 Try default

34 An Example pxeboot Session boot: F1

35 An Example pxeboot Session boot: fedora.c2in<enter>

36 An Example pxeboot Session: DHCP and TFTP Jul 9 21:07:09 hpvpw1 dhcpd: DHCPDISCOVER from 00:0c:29:dc:1b:a5 via eth0 Jul 9 21:07:09 hpvpw1 dhcpd: DHCPOFFER on to 00:0c:29:dc:1b:a5 \ via eth0 Jul 9 21:07:12 hpvpw1 dhcpd: DHCPREQUEST for ( ) \ from 00:0c:29:dc:1b:a5 via eth0 Jul 9 21:07:12 hpvpw1 dhcpd: DHCPACK on to 00:0c:29:dc:1b:a5 via eth0 Jul 10 04:07:12 hpvpw1 in.tftpd[9518]: RRQ from filename pxelinux.0 Jul 10 04:07:12 hpvpw1 in.tftpd[9518]: tftp: client does not accept options Jul 10 04:07:12 hpvpw1 in.tftpd[9519]: RRQ from filename pxelinux.0 Jul 10 04:07:12 hpvpw1 in.tftpd[9520]: RRQ from filename \ pxelinux.cfg/ c-29-dc-1b-a5 Jul 10 04:12:18 hpvpw1 in.tftpd[9564]: RRQ from filename help.txt Jul 10 04:14:08 hpvpw1 in.tftpd[9580]: RRQ from filename RfC2/vmlinuz Jul 10 04:14:08 hpvpw1 in.tftpd[9581]: RRQ from filename \ RfC2/initrd.img

37 The Network Boot Sequence with pxelinux and DHCP

38 Lab #1: DHCP, TFTP, pxelinux, and the Linux initrd See Lab #1 Handout for details

39 Section 3: Network Installation with Red Hat anaconda

40 The Red Hat anaconda Installer The anaconda installer is the graphical- or textbased installation tool that is familiar to anyone who has previously installed Red Hat Linux This installer is being used in the Fedora releases Manual configuration steps are saved in the /root/anaconda-ks.cfg file and may be used to recreate the installation without user intervention The kickstart configuration file may be made available on floppy, CD-ROM, or over the network The installer may be made available from CD-ROM or over the network

41 Red Hat anaconda and kickstart The Red Hat installation system is based on the RedHat Package Manager, RPM A package installation must unpack the files from the package and execute configuration scripts contained in the package This process is repeated for every package on every system that is installed What do you do if you have software that is not part of an RPM package? The post-installation script is one way to deal with this, and system image installation (upcoming) is another I have seen some architects throw the entire kickstart installation away and do everything in the post-installation script

42 Manual anaconda Installs Over the Network The Red Hat and Fedora media contain the kernel, vmlinuz and initial RAM disk, initrd.img needed to do a network installation These are located under RedHat/images/pxeboot on the installation media To use them, we need to put them into /tftpboot and make them known to the pxelinux facility We can boot the installation kernel and point it at the NFS, FTP, or HTTP location that contains the RPM packages from the installation media The installer can also use ISO images of the installation media to do the install (so you don t have to duplicate the packages and the ISO images for a particular distribution)

43 The pxelinux Configuration Entries in default.netboot Manual Installation label fedora.c2in kernel RfC2/vmlinuz append vga=extended load_ramdisk=1 initrd=rfc2/initrd.img Unattended Installation with kickstart label fedora.ksc2 kernel FkC2/vmlinuz append vga=extended load_ramdisk=1 initrd=fkc2/initrd.img \ ks=nfs: :/kickstart/ks.fc2/ The trailing slash indicates that the information is a directory to search for a <client-ip>-kickstart file, which can be a link

44 An Example Unattended kickstart file, ks.cfg (part 1) # Kickstart file automatically generated by anaconda. [modified RwL] install nfs --server=hpvpw1 --dir=/bigdata/linuxbase/install/fedoracore2/fedora cdrom lang en_us.utf-8 langsupport --default en_us.utf-8 en_us.utf-8 keyboard us mouse generic3ps/2 --device psaux xconfig --card "Intel 810" --videoram hsync vsync resolution 1024x768 --depth 24 --startxonboot --defaultdesktop gnome network --device eth0 --bootproto dhcp rootpw --iscrypted $1$CvYYIEvU$2dTwrsY7nJ9JALZrKmia7. firewall --disabled authconfig --enableshadow --enablemd5 timezone America/Los_Angeles

45 An Example Unattended kickstart file, ks.cfg (part 2) bootloader --location=partition --append hdd=ide-scsi rhgb clearpart --linux part raid.8 --size=100 --ondisk=hda --asprimary part raid.9 --size=100 --ondisk=hdc --asprimary part raid.12 --size= ondisk=hdc part raid.11 --size= ondisk=hda --asprimary part raid.15 --size=509 --ondisk=hdc part raid.14 --size=509 --ondisk=hda raid /boot --fstype ext3 --level=raid1 raid.8 raid.9 raid / --fstype ext3 --level=raid1 raid.11 raid.12 raid swap --fstype swap --level=raid1 raid.14 raid.15 everything kernel grub %post

46 What is in the /kickstart directory? Specific configuration files for different system types Links from <client-ip>-kickstart to the correct kickstart configuration file As a matter of fact, this looks just like the contents of the /tftpboot/pxelinux.cfg directory I use a variation of the make_links script that was presented previously It is a good idea to make sure that the system reinstallation, while unattended, is not automatic. I make sure that pxelinux has to select the install.

47 Populating the /kickstart Directory for Clients #!/bin/bash -x SCRIPT="ks.cfg" if [ -n "${1}" ]; then SCRIPT="${1}" fi for HOSTIP in $( sed 's@#.*$@@' < IPS ) do [[ -f "${HOSTIP}-kickstart" ]] && continue ln -s "${SCRIPT}" "${HOSTIP}-kickstart" done This script will skip over existing links that match the name format. So you can create the special cases, and then make the defaults # Nec # HpPav # HpEpc # Nec # HpXw4100

48 System Image Installation The SystemImager facility allows capturing the structure of a system, including the partition configuration and then re-installing or cloning it The SI installation is file-based, so the package manipulation overhead is removed SI is extremely flexible, so much so that we do not have time to cover all of its capabilities An SI server can capture a system s configuration in two steps: prepareclient is run on the golden client, then getimage is run on the server SI saves the image tree with rsync and can update file changes back to the clients without a reinstallation

49 SystemImager System Overview

50 SystemImager Updates with updateclient

51 SystemImager Operation SI boots a special kernel and initial RAM disk The start-up script in the SI initrd performs the following highlevel steps: starts the network interface configures the local disk partitions obtains the configuration script for the client image executes rsync to move the image from the server to the local disk reboots the client The configuration script may be modified to alter the behavior of the installation or to amend the disk partitioning steps System-specific overrides may be applied to make modifications to standard images without capturing a whole new client configuration Your network and the SI server must be capable of sustaining the traffic, or the number of simultaneous installations will be limited (in practice, a GbE can install systems at once if the server configuration is adequate)

52 Lab #2: Network Installations with anaconda, kickstart, and SystemImager See Lab #2 Handout for details

53 Section 4: Multicast Installations

54 Network Multicasting Multicasting is similar to broadcasting, however A system must subscribe to a multicast channel to receive the information Switching equipment may track which systems are subscribed and not flood frames to the ports that do not want it A special address range (class D) is used for multicasting traffic There are protocols for managing multicast traffic that we won t cover here Multicasting uses UDP, so there is low overhead, but no error correction or retransmission (UDP!= U Drop Packets ) There is a general-purpose tool, called udpcast that allows sending and receiving multicast data, it is available at The udpcast package provides a client and a server command, udp-receiver and udp-sender respectively The udpcast tools implement forward error correction (FEC) to allow reliable recovery from transmission problems These tools are used by the SI multicast facility, flamethrower

55 Network Multicast Address Formats

56 Why Multicasting? A single data stream may be used by as many clients as necessary (install 200 in the same time as for one) Lower server overhead Lower network overhead (single stream per install as opposed to single stream per client) A great idea!

57 The SI flamethrower Facility The flamethrower functionality is an add-on to the standard SI installation facility A multicast installation is triggered by special DHCP parameters passed to the client option option-143 code 143 = string; # (only for ISC's dhcpd v3) option option-143 "9000"; The DHCP client in the installation kernel passes this information to the installation script, which uses the value as the port for the multicast client software, udp-receiver The client locates the multicast session and attaches to the waiting udp-sender, which is managed by the flamethrowerd on the SI server

58 The SI flamethrower Facility Using a timed wait feature of the udp-sender, the multicast session waits for a set period of time When the wait period expires, the flamethrowerd sends a directory of the files to all multicast clients, which may then pick and choose what they want The files are multicast to the waiting clients, and the error-correction and retry behavior is adjustable Any clients that attempt to attach to the session after the wait period expires will be serviced by another session (the flamethrowerd daemon tracks this)

59 The SI flamethrower Facility Performs Multicast Installs

60 Lab #3: Multicast Installations with SystemImager s flamethrower See Lab #3 Handout for details

61 Summary Network installation is a useful approach to unattended, automated system installation The network installation tools for Linux are all based around the standard boot process involving a kernel and initrd file The infrastructure for network booting usually involves a PXE or DHCP feature in the system boot ROM, as well as the DHCP and TFTP servers Using pxelinux gives you a way to select multiple installation types interactively or automatically We covered manual anaconda installation, automatic kickstart installation, standard SystemImager installation, and SI multicast installation The choice of package-based or image-based installation methods can affect the scalability of your network installation process The use of multicast installations provides the best server and network economy per client being installed Once the learning curve is conquered, network installations are fast, efficient, and truly labor-saving!

62 Time for questions or test-driving. Thank you for coming.