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DNSMASQ"> Cluster DNSMASQ

• Setup dnsmasq - provides DHCP, DNS ad, TFTPBOOT services for the cluster

Makefile

• make is the only file run by and admin to update himrods dnsmasq settings
• compiles mkhosts.c
• runs install_dnsmasq
• Note: make can be run at ANY time to make sure all files are up to date

install_dnsmasq

• Only called from make ( ie. Makefile ) to install and configure dnsmasq using files defined in the following sections
• Stops nscd and dnsmasq
• updates /etc/resolv.conf using resolv.template files
• updates /etc/dnsmasq.hosts usings hsosts.template
• creates /etc/hosts , /etc/resolv.conf and /etc/dnsmasq.hosts
  • Updates /etc/dnsmasq.conf to include /etc/dnsmasq.hosts
• creates /etc/Networkmanager/dispatcher.d/00-dnsmaq trigger script to rewrite /etc/resolve.conf in case Network Manager is installed
  • This prevents other programs from messing up /etc/resolv.conf
• starts nscd and dnsmasq

DNSMASQ Config files

dnsmasq.common.himrod

• himrod specific configuration for dnsmasq
• Put all IP,MAC address and interface information for the cluster here * DNSMASQ
  • • /cscf-adm/src/dnsmasq contains all configuration files used for
    • * Depends on /etc/network/interfaces to have all interfaces defined statically
      • DHCP and DNS
      • /cscf-adm/src/dnsmasq/dnsmasq.common.himrod
        • The scripts assume dnsmasq.common. so replace himrod with your server
        • Defines all nodes and interfaces with simplified IP and MAC address notation
        • provides DNS and reverse DNS for all local networks
        • Example:

                         # Private Network
                         iface=em3
                         subnet=192.168.1
                         1,c8:1f:66:dd:f0:cc,himrod
                         10,c8:1f:66:df:69:7c,himrod-storage
                         11,c8:1f:66:dd:d8:ee,himrod-big-1
                         12,c8:1f:66:dd:db:3b,himrod-big-2
                         13,c8:1f:66:dd:d7:62,himrod-big-3
                         14,c8:1f:66:dd:f1:44,himrod-big-4
                         101,c8:1f:66:dd:da:1a,himrod-1
                         ...
                         <verbatim>
                         * Example DNS query after dnsmasq is running: 
                            * *host himrod*
                               * *himrod.localnet has address 192.168.1.1*
                            * *host himrod.cs*
                               * *himrod.cs has address 129.97.152.5*
          
          
          
          ---++++ dnsmasq.common
             * just a symlink to *dnsmasq.common.himrod* created by make install process
          
          ---+++ DNSMASQ Template Files
             *  * These files are preprocessed and added to the top of the automatically generated */etc/dnsmasq.hosts* file
                * *dnsmasq/dnsmasq.template.private*
                   * default DNSMASQ settings for ONE private network
                * *dnsmasq/dnsmasq.template.private_two*
                   * default DNSMASQ settings for TWO private networks
                * *dnsmasq/dnsmasq.template.private_three*
                   * default DNSMASQ settings for THREE private networks
                * *dnsmasq/hosts.template* 
                   * defines fixed records we always want in the */etc/hosts* file
                * *dnsmasq/resolv.template*
                   * defines fixed record we want added to the top of the */etc/resolv.conf* file
                   * Default external DNS servers - should be moved into [[https://cs.uwaterloo.ca/twiki/pub/CF/HimrodTools/common_host][common_host]]
          
          ---+++ DNSMASQ Compiled files
             * To recreate these files:
                * *cd /cscf-adm/src/dnsmasq*
                * *make*
          ---++++ /etc/hosts
             * Create from *mkhosts* and *install_dnsmasq* using *dnsmasq.common.himrod* and *hosts.template*
          
          ---++++ /etc/resolv.conf
             * Create from *mkhosts* and *install_dnsmasq* using *resolv.template*
          
          ---++++ /etc/dnsmasq.hosts
             * Create from *mkhosts* and *install_dnsmasq* using dnsmasq template files
          
          ---+++ dnsmasq.compiled.himrod
             * The top level include for dnsmasq created by the make install process
             * includes preporocessed *dnsmasq.template* files
             * includes *dnsmasq.common*
          
          ---+++ DNSMASQ mkhosts and mkhosts.c
             * preprocessor program that reads *dnsmasq.common.himrod*
                * *dnsmasq.compiled.himrod* and *hosts.template*
                * Writes */etc/dnsmasq.hosts* - a file included from the otherwise totally blank */etc/dnsmasq.conf* file
                * Write */etc/hosts*
                * Creates DHCP entries, *DNS* records - both forward and reverse lookups for local networks
          
          ---++++ mkhosts Ducumenation
             * What: mkhosts.c a preprocessor for dnsmasq configuration files
             *  The preprocessor handles creating reverse dns records and settings from
             *  a simpilfied syntax
             *  Syntax:
             *  *ttl=* time 
             *     *time* is a ttl as per the *dnsmasq* man pages
             *     Example: *ttl=1440m* - set the default ttl to 1440 minutes until the next ttl keyword
             *  * *subnet=* *subnet* specify the subnet
             *     *subnet* is a subnet specification - *LIMITATIONS* mkhosts uses hard coded /24 network - first 24 bits
             *     Example: *subnet=192.168.1* - this defines the subnet the same as 192.168.1.0 .. 192.168.1.255
             *  *ip*,*mac*,*cname* [,*cname*]...
             *     *ip* is the last digit of the subnet only
             *     *mac* is the MAC address of the interface you want to assign the address to
             *     *cname* a common separated list of cnames
             *  Example: 101,00:25:90:29:eb:ec,m160-1-local-comm,m160-1
             *     * Creates  
             *     <verbatim>
             *     dhcp-host=192.168.2.101,00:25:90:29:eb:ec,m160-1-local-comm,1440m
             *     ptr-record=101.2.168.192.in-addr.arpa.,"m160-1-local-comm"
             *     address=/m160-1-local-comm/192.168.2.101
             *     cname=m160-1,m160-1-local-comm
             *     </verbatim>
             *  *prefix=* We can redefine dhcp name prefix for reverse lookups
             *  *iface=* just puts a comment in the output file
             *  *tag=* defind tags to be appened to dhcp-host
             *  *pxelinux=* Define the pxelinux subnet - hosts under this section can get a private boot file
             *     Each mac address will simlink to the file pxelinux.cfg/nodes
             *  *include=* process an include file
             *  
             *  Example:
             *   ttl=1440m
             *   subnet=192.168.2
             *   1,00:25:90:0e:5b:a2,m160-local-comm,m160-comm,m160
             *   101,00:25:90:29:eb:ec,m160-1-local-comm,m160-1
             *   ...</verbatim>
          <nop>