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| [[Category:Linux]] | | [[Category:Linux]] |
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− | =Context and aim=
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− | ==Aim==
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− | I want to achieve the following configuration:
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− | [[File:Smartcards network.png|none|Target network diskless configuration]]
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− | Key points:
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− | * Each client is a diskless station.
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− | * I want to use the same distribution everywhere.
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− | For all this tutorial I'll be using a local network 172.16.50.0/24 with 172.16.50.2 as master server.
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− | '''Diskless''' station means:
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− | The clients don't need any hard drive to run, they will retrieve the file system from the TFTP server and use a NFS share as hard drive. The system will only run in RAM disk. So:
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− | * All the clients will share the installation, configuration files and so on.
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− | * Each client will run a dedicated instance of the operating system in his own RAM disk
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− | * Logs will be centralized on the common NFS server - so we don't loose data on each reboot.
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− | * The user will be able to choose the O.S to run on boot - thanks to a PXE menu
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− | Monitoring point of view:
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− | * Each client will have a local '''SNMP agent''' + a dedicated '''zabbix agent''' to send back its status. In my case, as I'm using Java, I'll install the Oracle JDK and I will use some '''JMX''' beans too.
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− | * The current server ''smartcard-gw'' will also have a '''SNMP agent''' + a dedicated '''zabbix agent''' so I can monitor it too.
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− | File access:
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− | * The common NFS share will be exposed by a Samba server as a network file-share. Therefore I'll be able to browse for it and access it easily.
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− | ==Requirements==
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− | To achieve that you need to have:
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− | * [[DHCP server]]
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− | * [[NetBoot server]]
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− | Optional:
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− | * [[DNS server]]
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| By default the ''deboostrap'' Ubuntu 14.04 LTS image is 239 Mo. With the applications we're gonna use that size will increase to about 1 or '''1.3 Go''' depending if you copy (or not) the kernel sources. It may even take 1.6 Go if you're using XFCE frontend. | | By default the ''deboostrap'' Ubuntu 14.04 LTS image is 239 Mo. With the applications we're gonna use that size will increase to about 1 or '''1.3 Go''' depending if you copy (or not) the kernel sources. It may even take 1.6 Go if you're using XFCE frontend. |
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− | =Installation=
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− | '''NFS support'''
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− | <syntaxhighlight lang="bash">
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− | apt-get install nfs-kernel-server nfs-common
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− | </syntaxhighlight>
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− | '''Debootstrap (manage netboot image)'''
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− | <syntaxhighlight lang="bash">
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− | apt-get install debootstrap
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− | </syntaxhighlight>
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− | '''Initramfs (to manage "virtual disks")'''
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− | <syntaxhighlight lang="bash">
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− | apt-get install initramfs-tools
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− | </syntaxhighlight>
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− | =Preparation=
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− | You have to create a dedicated folder on your server where you will host the distributions kernels + Boot settings.
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− | <syntaxhighlight lang="bash">
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− | mkdir -p /tftpboot/pxelinux.cfg
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− | chmod -R 755 /tftpboot/pxelinux.cfg
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− | mkdir -p /tftpboot/images
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− | chmod -R 755 /tftpboot/images
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− | </syntaxhighlight>
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− | The ''pxelinux.cfg/'' folder is mandatory. Inside you can provide:
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− | * configuration for a specific IP @ or hostname
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− | * configuration for a group
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− | * default configuration (required)
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− | =Boot menu and Kernel setup=
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− | The first thing to do is to setup a booting kernel. To do so we'll use the "syslinux" files.
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− | '''Reminder'''
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− | If your client(s) will use some smart-cards driver then you MUST install these drivers on the on the NFS server + reboot the server ; before going through the following steps. See [[Drivers#Smart-card_drivers]]
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− | ==Root file: pxelinux.0==
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− | The '''pxelinux.0''' is the root file. That's the file that allows the netboot.
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− | This is the file that is serve by the TFTP server.
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− | <syntaxhighlight lang="bash">
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− | cp /usr/lib/syslinux/pxelinux.0 /tftpboot/
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− | </syntaxhighlight>
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− | ==Create NetBoot menu | defaults==
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− | Now, we have to specify which kernel to use and which distributions are available for NetBoot.
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− | Create the default configuration file:
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− | <syntaxhighlight lang="bash">
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− | vim /tftpboot/pxelinux.cfg/default
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− | </syntaxhighlight>
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− | Put the following:
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− | <syntaxhighlight lang="bash">
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− | # Debian 7.x
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− | LABEL wheezy
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− | kernel images/wheezy/vmlinuz
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− | initrd images/wheezy/initrd.img
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− | # Ubuntu 14.04
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− | LABEL trusty
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− | kernel images/trusty/vmlinuz
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− | initrd images/trusty/initrd.img
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− | # Prompt user for selection
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− | PROMPT 1
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− | # No timeout
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− | TIMEOUT 0
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− | </syntaxhighlight>
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− | * Each LABEL is a specific configuration that will displayed on the NetBoot menu.
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− | * PROMPT 0 = enable user prompt so you can choose the configuration
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− | * TIMEOUT 0 = timeout (in seconds) before the default option is chosen. 0 == no timeout
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− | Note that I used a reference to "trusty/", that's a folder I need to create later on.
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− | ==Init Kernel files==
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− | ===Create directories===
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− | Create the target kernel folders. You should create 1 folder for each distribution you'd like to provide in NetBoot.
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− | <syntaxhighlight lang="bash">
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− | # Debian 7.x
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− | mkdir -p /tftpboot/images/wheezy
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− | # Ubuntu 14.04
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− | mkdir -p /tftpboot/images/trusty
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− | </syntaxhighlight>
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− | ===Prepare ''initramfs'' to boot over NFS===
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− | '''This step must to be run on the machine that has the kernel you are going to serve to your clients'''.
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− | >>> In our case it has to be run on the TFTP server
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− | Copy initramfs settings for PXE boot
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− | <syntaxhighlight lang="bash">
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− | cp -r /etc/initramfs-tools /etc/initramfs-pxe
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− | </syntaxhighlight>
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− | Adjust PXE boot configuration
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− | <syntaxhighlight lang="bash">
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− | cd /etc/initramfs-pxe/
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− | vim /etc/initramfs-pxe/initramfs.conf
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− | </syntaxhighlight>
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− | Add / adjust the following options:
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− | <syntaxhighlight lang="bash">
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− | BOOT=nfs
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− | MODULE=netboot
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− | </syntaxhighlight>
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− | ===Copy and prepare kernel===
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− | You have to copy your current kernel files to the boot folder:
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− | <syntaxhighlight lang="bash">
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− | # Debian 7.x
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− | cp /boot/vmlinuz-`uname -r` /tftpboot/images/wheezy/vmlinuz
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− | cp /boot/initrd.img-`uname -r` /tftpboot/images/wheezy/initrd.img
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− | # Ubuntu 14.04
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− | cp /boot/vmlinuz-`uname -r` /tftpboot/images/trusty/vmlinuz
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− | cp /boot/initrd.img-`uname -r` /tftpboot/images/trusty/initrd.img
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− | </syntaxhighlight>
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− | Enable NFS boot on target kernel:
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− | <syntaxhighlight lang="bash">
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− | mkinitramfs -d /etc/initramfs-pxe -o /tftpboot/images/trusty/initrd.img
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− | </syntaxhighlight>
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− | Adjust rights:
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− | <syntaxhighlight lang="bash">
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− | chmod -R 755 /tftpboot/images/
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− | </syntaxhighlight>
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− | Notes:
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− | * Do NOT use some symlink for "vmlinuz" and "initrd.img" !! It won't work.
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− | * If you don't want to use `uname -r` [current kernel version and architecture] then adjust the values to target kernel number + architecture
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− | * You have to run ''mkinitramfs'' for each kernel you'll provide
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− | * Don't forget to adjust the rights to 755 for every distribution
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− | =NFS server setup=
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− | ==Configuration==
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− | The NFS configuration is done in the '''/etc/exports''' file
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− | <syntaxhighlight lang="bash">
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− | vim /etc/exports
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− | </syntaxhighlight>
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− | Add something like that:
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− | <syntaxhighlight lang="bash">
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− | ### list of available O.S
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− | /nfs/trusty 172.16.50.0/24(ro,no_root_squash,no_subtree_check,async,insecure)
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− | /nfs/wheezy 172.16.50.0/24(ro,no_root_squash,no_subtree_check,async,insecure)
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− | ### common share
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− | /nfs/common 172.16.50.0/24(rw,no_root_squash,no_subtree_check,async,insecure)
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− | </syntaxhighlight>
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− | Adjust "172.16.50.0/24" to your own network address
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− | * rw : Allow clients to read as well as write access
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− | * ro : Read only access
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− | * insecure : Tells the NFS server to use unpriveledged ports (ports > 1024).
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− | * no_subtree_check : If the entire volume (/users) is exported, disabling this check will speed up transfers.
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− | * async : async will speed up transfers.
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− | * no_root_squash: This phrase allows root to connect to the designated directory.
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− | - NOTE -
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− | * It's always a good idea to use Read-Only if you plan to share this disk. That will avoid user to mess with your image!
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− | * There must not be any space between network IP and "("
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− | * If you plan to share a NFS to all users - like my '''/nfs/common''' - don't forget to set ''chmod -R 777 /nfs/common''
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− | ==Security==
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− | Like TFTP, this part is insecure !
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− | You must restrict the access to your NFS server by a firewall script and filtering BEFORE reaching the LAN !
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− | NFS is using dynamic ports numbers because it runs over '''rpcbind'''. Making NFS using specifics port is a pain in the ass !! :(
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− | So, instead of that you should allow your LAN communication.
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− | <syntaxhighlight lang="bash">
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− | IPTABLES=`which iptables`
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− | LAN_ADDRESS="172.16.50.0/24"
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− | # Allow LAN communication
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− | $IPTABLES -A INPUT -s $LAN_ADDRESS -d $LAN_ADDRESS -m state ! --state INVALID -j ACCEPT
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− | $IPTABLES -A OUTPUT -s $LAN_ADDRESS -d $LAN_ADDRESS -m state ! --state INVALID -j ACCEPT
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− | </syntaxhighlight>
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− | ==Management==
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− | <syntaxhighlight lang="bash">
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− | service nfs-kernel-server {status|start|stop|restart}
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− | </syntaxhighlight>
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− | ==Test the server==
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− | Install the NFS v4 client:
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− | <syntaxhighlight lang="bash">
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− | apt-get install nfs-common
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− | </syntaxhighlight>
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− | To mount the default path:
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− | <syntaxhighlight lang="bash">
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− | mount -t nfs nfs-server:/ /mnt
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− | </syntaxhighlight>
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− | You'll see: "/nfs"
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− | It's better to do:
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− | <syntaxhighlight lang="bash">
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− | mount -t nfs nfs-server:/nfs /mnt
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− | </syntaxhighlight>
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| * Automatic [Puppet || Chef] configuration: [[Diskless image configuration - script setup]] | | * Automatic [Puppet || Chef] configuration: [[Diskless image configuration - script setup]] |
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− | ==Kernel modules and source==
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− | -- This is an optional step ; but it can avoid many bugs --
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− | If you're using a local kernel as the default NetBoot kernel, then you need to do copy the ''modules'' + ''kernel source'' to every distribution.
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− | <syntaxhighlight lang="bash">
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− | # Copy kernel modules
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− | cp -r /lib/modules/`uname -r` /nfs/trusty/lib/modules
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− | # Copy kernel sources
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− | cp -r /usr/src/linux-headers-`uname -r` /nfs/trusty/usr/src
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− | </syntaxhighlight>
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− | Note that '''you have to adjust the /nfs'''/XXX
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− | =File sharing= | + | =Other services= |
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| + | ==File sharing== |
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| If you want to expose the NFS common folder as a file-share, you have to install and configure Samba. See: [[Samba server]] | | If you want to expose the NFS common folder as a file-share, you have to install and configure Samba. See: [[Samba server]] |
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| + | ''Note'' |
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| + | Samba is actually better than NFS for the file-share. You should remove Common from /etc/exports and use a samba share instead. |
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| + | ==Management UI (webmin)== |
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| + | Since there is a lot of services to manage, it's always convenient to use an UI for it. Check [[Webmin]] |
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| + | ==VPN server== |
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| + | See [[VPN]] |
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| + | ==Apache2 server== |
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| + | See [[Apache 2]] |
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Target folder tree (server side)
This is how we'll setup our files and folders:
# TFTP root
/tftpboot/
###############
# Network bootable image(s) using NFS technology
################
#### Boot file
/tftpboot/pxelinux.0 # Initial boot file - only use to load the PXE NetBoot manager
/tftpboot/{menu.c32 || vesamenu.c32} # PXE interactive menu managers (text or graphical)
/tftpboot/pxelinux.cfg/ # PXE configuration(s)
/tftpboot/pxelinux.cfg/default # default PXE configuration
#### Kernel file
/tftpboot/images/
# Debian 7.x [Wheezy]
/tftpboot/images/wheezy/
/tftpboot/images/wheezy/vmlinuz
/tftpboot/images/wheezy/initrd.img
# [X]Ubuntu 14.04 [Trusty]
/tftpboot/images/trusty/
/tftpboot/images/trusty/vmlinuz
/tftpboot/images/trusty/initrd.img
#### NFS
# This is where the runnable will be. Each image will be in a dedicated folder.
/nfs/
# Debian 7.x [Wheezy]
/nfs/wheezy/
# Ubuntu 14.04 [Trusty]
/nfs/trusty/
Client overview
Each client must have, at least, 4 Go of RAM.
4 GO RAM configuration
This is how we're gonna populate the client:
As you can see, each client will have some space dedicated for swap + some RAMdisk to allow writing in /var, /tmp and /proc.
Configuration of a 4Go RAM disk:
- No swap
- Local TMPFS (read/write for /dev, /tmp, ...) : 1 Go
- /tmp = 512 M
- /var/tmp = 128 M
- /var/log = 128 M
- /var/run = 8 M
- /var/lock = 8 M
- /run/shm = 256 M
- O.S (NFS read only) : all the rest ~ 2.8 Go
- Common share (NFS read write) : Remote disk
2 Go
Due to budget restriction we might encounter some low memory machines with only 2 Go...
This is how we're gonna populate the client:
In case of 2Go RAM then you have to use some tricks:
- No swap
- O.S (NFS read only) : ~ 1.2 Go
- Common share (NFS read write) : Remote disk
- Local TMPFS (read/write for /dev, /tmp, ...) : all the rest
- /tmp = 372 M
- /var/tmp = auto
- /var/log = 128 M
- /var/run = auto
- /var/lock = auto
- /run/shm = auto
How big is the client image ?
By default the deboostrap Ubuntu 14.04 LTS image is 239 Mo. With the applications we're gonna use that size will increase to about 1 or 1.3 Go depending if you copy (or not) the kernel sources. It may even take 1.6 Go if you're using XFCE frontend.
NFS client image
There are different way to setup a NFS client image.
The main ones are:
- Manually
- debootstrap
- copying the install from your server
- Manual install on a client, then, when the system is ready, copy everything to the NFS share
- Using script and software like "Puppet" or "Chef"
Setup client distribution
You have to create one target for each distribution you want to serve:
mkdir -p /nfs/trusty
mkdir -p /nfs/wheezy
mkdir -p /nfs/common
- NOTES -
- The folder name should match your NetBoot settings. Folder name = a LABEL in the NetBoot config.
- The folder name should match a Linux (Debian like) distribution name
Configure client distribution
Backup distribution
You can create an archive of your current distribution for later restore / re-use.
Compression
cd /nfs
tar cvpjf trusty.tar.bz2 ./trusty
Restoration
cd /nfs
tar -xvjf trusty.tar.bz2
You can create interactive NetBoot menus, see:
Local server monitoring
Install the following services:
Other services
File sharing
If you want to expose the NFS common folder as a file-share, you have to install and configure Samba. See: Samba server
Note
Samba is actually better than NFS for the file-share. You should remove Common from /etc/exports and use a samba share instead.
Management UI (webmin)
Since there is a lot of services to manage, it's always convenient to use an UI for it. Check Webmin
VPN server
See VPN
Apache2 server
See Apache 2
References
Ubuntu diskless how-to: https://help.ubuntu.com/community/DisklessUbuntuHowto
Mind reference: http://mindref.blogspot.se/2011/03/debian-diskless.html
Super video tutorials:
Nice explanation of PXE process: http://www.linux.com/learn/docs/ldp/497-Diskless-root-NFS-HOWTO