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DNSMASQ

• ASIMOV configuration
• Note: in the document DNSMASQ refers to the dnsmasq scripts home directory

Rererences

• https://cs.uwaterloo.ca/twiki/view/CF/UEFI

DNSMASQ-MULTIARCH

• DNSMASQ-MULTIARCH Example configuration to support BIOS and UEFI clients

Summary

• What: dnsmasq is a single package that provides PXE BOOT, DNS, DHCP services

Dependencies

• Get the minimal PXE boot file set from ASIMOV PXEBootFilesExample
• Get the NAT Private network MASQ firewall scripts from ASIMOV NatMasqFirewallExample
• I Strongly suggest that you REMOVE and PURGE networkmanager and resolveconf packages!
  • apt-get remove --purge network-manager
  • apt-get remove --purge resolveconf
    • Note - side effect is that optional dns-nameserver lines in /etc/network/interfaces will be ignored - so they have to be put in /etc/resolv.conf
  • Then configure /etc/network/interfaces manually:
    • DHCP

            # This file describes the network interfaces available on your system
            # and how to activate them. For more information, see interfaces(5).
      
            # The loopback network interface
            auto lo
            iface lo inet loopback
      
            # The primary network interface
            auto eth0
            iface eth0 inet dhcp
            

    • STATIC

            # This file describes the network interfaces available on your system
            # and how to activate them. For more information, see interfaces(5).
      
            # The loopback network interface
            auto lo
            iface lo inet loopback
      
            # STATIC Configuration for eth0
            auto eth0
            iface eth0 inet static
             address 129.97.xxx.xxx
             netmask 255.255.255.0
             broadcast 129.97.xxx.255
             network 129.97.xxx.0
             gateway 129.97.xxx.1
             mtu     1492
            

    • Warnings - if your machine was imaged your network may NOT be eth0
      • Post imaging should always do a rm /etc/udev/rules.d/70-persistent-net.rules
      • So you may have to do this and reboot - only if your default is not eth0 already
      • Why? because the 70-persistent-net.rules saves the MAC address of each interface it sees so every machine a system is imaged from will increment one higher eth1,eth2 ....

Install

• Location: asimov.uwaterloo.ca:/images/exports/dnsmasq
• Install: rsync -a cscf-adm@asimov.uwaterloo.ca:/images/exports/dnsmasq/ /root/dnsmasq

References

• • See also ImageDeploymentGhost#Network_Boot_Images_PXE_booting

Hosts using these scripts

• asimov.cscf.uwaterloo.ca, m160.cs.uwaterloo.ca, novo1.cs.uwaterloo.ca, cabernet.cs.uwaterloo.ca husky.cs chardonnay.cs himrod.cs

Host specific configuration files

The following files are the DNSMASQ configuration files that you have to update for a new system. You will also need the dependencies listed in the previous sections

DNSMASQ/hosts.common

• Used to help create the start section of /etc/hosts
• Change the Head Node name your your hosts external address
• Optionally add any address you want - but NO node addresses - that goes in DNSMASQ/dnsmasq.source.`hostname` (without the .cs or extension )

     127.0.0.1       localhost
     127.0.1.1       localhost
  
     # The following lines are desirable for IPv6 capable hosts
     ::1     localhost ip6-localhost ip6-loopback
     fe00::0 ip6-localnet
     ff00::0 ip6-mcastprefix
     ff02::1 ip6-allnodes
     ff02::2 ip6-allrouters
  
     # Backup server
     129.97.167.240 backup-0.cs.uwaterloo.ca backup-0.cs backup-0 backup.cs.uwaterloo.ca backup.cs backup
     

DNSMASQ/resolv.common

• used to create /etc/resolv.conf - also used by Network Manager to rebuild /etc/resolv.conf

     search . cs.uwaterloo.ca uwaterloo.ca
     nameserver 127.0.0.1
     nameserver 172.19.32.5
     nameserver 172.19.32.6
     nameserver 172.19.47.6
     

DNSMASQ/dnsmasq.source.example

• example is the name of your host

     # We turn all lines in /etc/dnsmasq.conf to comments
     # Except the line: conf-file=/etc/dnsmasq.hosts
     
     # All configuration goes here
     # ONLY the listen-address line changes when moving this to a new host
  
     # ================================================================
     include=dnsmasq.common
     # ================================================================
     # ONLY the listen-address line changes when moving this to a new host
     
     # listen-address replaced with interface for this system
     # listen-address=127.0.0.1,192.168.2.1
  
     # Private VLAN on eth1 - you can add as many as you wish
     # Example 192.168.2.1
     interface=eth1
  
     # External interface
     except-interface=eth0
     no-dhcp-interface=eth0
  
     bind-interfaces
     #This program assumes that the dhcp-range is in the following order
     # tag,min,max,ttl
     dhcp-range=comm,192.168.2.2,192.168.2.254,255.255.255.0,12h
     dhcp-option=option:router,192.168.2.1
  
     # The option numbers below conform to DHCP RFC's
     # 3 = route
     # 6 = DNS
     dhcp-option=comm,3,192.168.2.1
     # a comma separated list of DNS servers at the end of this statement
     dhcp-option=comm,6,192.168.2.1
     # ==============================================================
  
     # ==============================================================
     # Syntax:
     # IP,MAC,NAME[,CNAME]
     # subnet=192.168.8   (currently only doing /24 networks)
     # ttl=1440m   (whatever dnsmasq accepts for ttl)
     # ==============================================================
  
     # COMM
     # eth1
     ttl=1440m
     subnet=192.168.2
     # Head Node Private Network Address
     1,00:25:90:18:e2:8f,head-node
     # Nodes
     101,00:25:90:29:eb:ed,node-1,node-1-local
     102,00:25:90:29:eb:f9,node-2,node-2-local
     103,00:25:90:2b:df:71,node-3,node-3-local
     

DNSMASQ/dnsmasq.common

• Common configuration for DNSMASQ - does not normal get changed

     resolv-file=/etc/resolv.conf
     dhcp-leasefile=/var/lib/misc/dnsmasq.leases
     local=/localnet/
     enable-tftp
     tftp-root=/tftpboot/pxes
     dhcp-boot=pxelinux.0
     dhcp-authoritative
     domain-needed
     bogus-priv
     strict-order
     

Helper scripts and programs

mkhosts and restart script

Overview

• DNSMASQ/mkhosts: compiles simplified source file into fully qualified /etc/dnsmasq.conf file*
• dnsmasq Provides services: * DNS * DHCP * PXE/TFTPBOOT
• DNSMASQ/restart - master dnsmasq control script - restarts and updates all dnsmasq and related services

Makefile

• running make compiles all configuration files and restarts dnsmasq with updated settings
• Source files
  • DNSMASQ/hosts.common
  • DNSMASQ/dnsmasq.source.`hostname` - primary simplified source
    • DNSMASQ/dnsmasq.common - typical include file
    • /etc/resolv.conf" - created from *DNSMASQ/resolv.common
    • /etc/hostname - not updated yet
• Services
  • DNSMASQ/Makefile - recompiles DNSMASQ/mkhosts and restarts dnsmasq
  • Adds conf-file=/etc/dnsmasq.hosts to /etc/dnsmasq.conf if it is not already there
  • Runs DNSMASQ/mkhosts -f DNSMASQ/dnsmasq.source.`hostname` -h DNSMASQ/hosts.common
  • Runs Network Manager trigger script to rebuild /etc/resolv.conf
  • Restarts dnsmasq and removes any old leases in the process
  • Restarts nscd
  • Backs up a copy of all DNSMASQ config files to *DNSMASQ/backups/`hostname`
  • Backs up a copy of all DNSMASQ related output files to *DNSMASQ/backups/`hostname`/output

mkhosts

• DNSMASQ.mkhosts - translates simplified source file into fully qualified /etc//dnsmasq.conf include
• Usage: DNSMASQ/mkhosts -f DNSMASQ/dnsmasq.source.`hostname` -h DNSMASQ/hosts.common
  • Output Files:
    • /etc/dnsmasq.hosts - Compiled /etc/dnsmasq.conf include file
    • /etc/hosts - Builds a /etc/hosts file from dnsmasq source files
    • /tftpboot/pxes/pxelinux.cfg/hostips - optional symlinks for per IP PXE booting
  • Source files
    • DNSMASQ/dnsmasq.source.`hostname` - Simplified dnsmasq source file
    • DNSMASQ/hosts.common - Include header for building /etc/hosts

/etc/NetworkManager/dispatcher.d/00-dnsmasq

• Network Manager trigger script - creates /etc/resolv.conf from DNSMASQ/resolv.common

*dnsmasq.source.*=hostname= Keywords

• 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

                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
               

• 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

Examples

Cluster novo1.cs

• We have three network interfaces that we want to supply DHCP,PXE BOOT, and DNS to

Source Files

DNSMASQ/mkhosts.c

• DNSMASQ/mkhosts.c

DNSMASQ/Makefile

• DNSMASQ/Makefile

DNSMASQ/restart

• DNSMASQ/restart

DNSMASQ/dnsmasq.common

• DNSMASQ/dnsmasq.common

DNSMASQ/dnsmasq.source.novo1

• DNSMASQ/dnsmasq.source.novo1

DNSMASQ/hosts.common

• DNSMASQ/hosts.common
• make sure you add the external IP address to just after 127.0.0.1

DNSMASQ/resolv.common

• DNSMASQ/resolv.common

Output Files

/etc/dnsmasq.hosts

• dnsmasq.hosts

/etc/hosts

• /etc/hosts

/etc/resolv.conf

• resolv.conf
• Make sure you add "." to the start of the search line

/etc/dnsmasq.conf

• /etc/dnsmasq.conf

PXE

• PXE BOOT /tftpboot/pxes
  • Config: /tftpboot/pxes/pxelinux.cfg/default
  • ISO boot images: /tftpboot/pxes/iso

/tftpboot/pxes/pxelinux.cfg/default

• /tftpboot/pxes/pxelinux.cfg/default