Configuration file for dnsmasq.
Listen on this specific port instead of the standard DNS port (53).
Setting this to zero completely disables DNS function, leaving only DHCP and/or TFTP.
The following two options make you a better netizen,
They tell dnsmasq to filter out queries which the public DNS cannot answer, and which load the servers (especially the root servers) unnecessarily.
If you have a dial-on-demand link they also stop
these requests from bringing up the link unnecessarily.
# Never forward plain names (no dot or domain) domain-needed # Never forward addresses that are non-routable bogus-priv
Uncomment these to enable DNSSEC validation and caching:
(Requires dnsmasq to be built with DNSSEC option.)
# conf-file=/usr/share/dnsmasq/trust-anchors.conf # dnssec
Replies which are not DNSSEC signed may be legitimate, because the domain unsigned, or may be forgeries.
Setting this option tells dnsmasq to
check that an unsigned reply is OK, by finding a secure proof that a DS record somewhere between the root and the domain does not exist.
The cost of setting this is that even queries in unsigned domains will need one or more extra DNS queries to verify.
Block SRV requests
Change this line if you want dns to get its upstream servers from
somewhere other that /etc/resolv.conf
By default, dnsmasq will send queries to any of the upstream
servers it knows about and tries to favour servers to are known
to be up. Uncommenting this forces dnsmasq to try each query
with each server strictly in the order they appear in
If you don't want dnsmasq to read /etc/resolv.conf or any other file, getting its servers from this file instead (see below), then uncomment this.
If you don't want dnsmasq to poll /etc/resolv.conf or other resolv files for changes and re-read them then uncomment this.
Add other name servers here, with domain specs if they are for
Example of routing PTR queries to nameservers: this will send all
address->name queries for 192.168.3/24 to nameserver 10.1.2.3
Add local-only domains here, queries in these domains are answered
from /etc/hosts or DHCP only.
Add domains which you want to force to an IP address here.
The example below send any host in double-click.net to a local web server
address=/double-click.net/127.0.0.1 # address=/www.thekelleys.org.uk/fe80::20d:60ff:fe36:f83
Add the IPs of all queries to yahoo.com, google.com, and their subdomains to the vpn and search ipsets:
You can control how dnsmasq talks to a server
this forces queries to 10.1.2.3 to be routed via eth1
this sets the source (ie local) address used to talk to
10.1.2.3 to 192.168.1.1 port 55
(there must be a interface with that
IP on the machine, obviously).
If you want dnsmasq to change uid and gid to something other than the default, edit the following lines.
# user= # group=
Specifiy which address to listen on
If you want dnsmasq to listen for DHCP and DNS requests only on specified interfaces (and the loopback) give the name of the interface (eg eth0) here.
Repeat the line for more than one interface.
Specify which interface not to listen on
Specify which address to listen on
(remember to include 127.0.0.1 if you use this.)
Only provide DNS on an interface (no dhcp)
If you want dnsmasq to provide only DNS service on an interface, configure it as shown above, and then use the following line to disable DHCP and TFTP on it.
Listen on all interface
On systems which support it, dnsmasq binds the wildcard address, even when it is listening on only some interfaces.
It then discards requests that it shouldn't reply to.
This has the advantage of working even when interfaces come and go and change address.
If you want dnsmasq to really bind only the interfaces it is listening on, uncomment this option.
About the only time you may need this is when running another nameserver on the same machine.
Ignore the /etc/hosts file
If you don't want dnsmasq to read /etc/hosts, uncomment the following line.
#no-hosts # # If you want it to read another file # in addition to /etc/hosts #addn-hosts=/etc/banner_add_hosts
Set this (and domain: see below) if you want to have a domain automatically added to simple names in a hosts-file.
Set the domain for dnsmasq.
This is optional, but if it is set, it does the following things.
- Allows DHCP hosts to have fully qualified domain names, as long as the domain part matches this setting.
- Sets the "domain" DHCP option thereby potentially setting the domain of all systems configured by DHCP
- Provides the domain part for "expand-hosts"
# domain=thekelleys.org.uk # Set a different domain for a particular subnet # domain=wireless.thekelleys.org.uk,192.168.2.0/24 #Same idea, but range rather then subnet #domain=reserved.thekelleys.org.uk,188.8.131.52,192.168.3.200
Uncomment this to enable the integrated DHCP server
You need to supply the range of addresses available for lease and optionally a lease time.
If you have more than one network, you will need to
repeat this for each network on which you want to supply a DHCP service.
This is an example of a DHCP range which sets a tag, so that some DHCP options may be set only for this network.
Use this DHCP range only when the tag "green" is set.
Specify a subnet which can't be used for dynamic address allocatiotion
THerefore, the subnet is only available for hosts with matching --dhcp-host lines.
Note that dhcp-host declarations will be ignored unless there is a dhcp-range of some type for the subnet in question.
Note that the prefix-length does not need to be specified
and defaults to 64 if missing
# dhcp-range=1234::2, 1234::500, 64, 12h
Do Router Advertisements, BUT NOT DHCP for this subnet.
# dhcp-range=1234::, ra-only # Do Router Advertisements, BUT NOT DHCP for this subnet try and add names to the DNS for the IPv6 address of SLAAC-configured dual-stack # Use the DHCPv4 lease to derive the name, network segment and MAC address and assume that the host will also have an IPv6 address calculated using the SLAAC algorithm. # dhcp-range=1234::, ra-names
Do DHCP6 and Router Advertisements for this subnet.
Set the A bit in the RA so that clients can use SLAAC addresses as well as DHCP ones.
# dhcp-range=1234::2, 1234::500, slaac
Do Router Advertisements and stateless DHCP6 for this subnet.
Clients will not get addresses from DHCP, but they will get other configuration information.
They will use SLAAC for addresses.
# dhcp-range=1234::, ra-stateless
Do stateless DHCP, SLAAC, and generate DNS names for SLAAC addresses from DHCPv4 leases.
# dhcp-range=1234::, ra-stateless, ra-names
Do router advertisements for all subnets where we're doing DHCPv6
Unless overridden by ra-stateless, ra-names, et al, the router advertisements will have the M and O bits set, so that the clients get addresses and configuration from DHCPv6, and the A bit reset, so the clients don't use SLAAC addresses.
Supply parameters for specified hosts using DHCP.
There are lots of valid alternatives, so we will give examples of each. Note that IP addresses DO NOT have to be in the range given above, they just need to be on the same network.
The order of the parameters do not matter, it's permissible to give name, address and MAC in any order.
# Set IP for host with mac # dhcp-host=11:22:33:44:55:66,192.168.0.60 #dhcp-host=11:22:33:44:55:66,fred # dhcp-host=11:22:33:44:55:66,fred,192.168.0.60,45m # Give a host with Ethernet address 11:22:33:44:55:66 or # 12:34:56:78:90:12 the IP address 192.168.0.60. Dnsmasq will assume # that these two Ethernet interfaces will never be in use at the same # time, and give the IP address to the second, even if it is already # in use by the first. Useful for laptops with wired and wireless # addresses. dhcp-host=11:22:33:44:55:66,12:34:56:78:90:12,192.168.0.60 # Give the machine which says its name is "bert" IP address # 192.168.0.70 and an infinite lease #dhcp-host=bert,192.168.0.70,infinite # Always give the host with client identifier 01:02:02:04 the IP address 192.168.0.60 #dhcp-host=id:01:02:02:04,192.168.0.60 # host with client identifier "marjorie" # the IP address 192.168.0.60 # dhcp-host=id:marjorie,192.168.0.60 # Enable the address given for "judge" in /etc/hosts # to be given to a machine presenting the name "judge" when t asks for a DHCP lease. # dhcp-host=judge # Never offer DHCP service to a machine whose Ethernet # address is 11:22:33:44:55:66 # dhcp-host=11:22:33:44:55:66,ignore # Ignore any client-id presented by the machine with Ethernet address 11:22:33:44:55:66. This is useful to prevent a machine # being treated differently when running under different OS's or # between PXE boot and OS boot. # dhcp-host=11:22:33:44:55:66,id:* # Send extra options which are tagged as "red" to # the machine with Ethernet address 11:22:33:44:55:66 # dhcp-host=11:22:33:44:55:66,set:red # Send extra options which are tagged as "red" to # any machine with Ethernet address starting 11:22:33: # dhcp-host=11:22:33:*:*:*,set:red
Give a fixed IPv6 address and name to client with a specified DUID
# dhcp-host=id:00:01:00:01:16:d2:83:fc:92:d4:19:e2:d8:b2, fred, [1234::5]
Ignore any clients which are not specified in dhcp-host lines or /etc/ethers.
Equivalent to ISC "deny unknown-clients".
This relies on the special "known" tag which is set when a host is matched.
Send extra options which are tagged as "red" to any machine whose
DHCP vendorclass string includes the substring "Linux"
Send extra options which are tagged as "red" to any machine one
of whose DHCP userclass strings includes the substring "accounts"
Send extra options which are tagged as "red" to any machine whose
MAC address matches the pattern.
If this line is uncommented, dnsmasq will read /etc/ethers and act on the ethernet-address/IP pairs found there, just as if they had been given as --dhcp-host options.
Useful if you keep MAC-address/host mappings there for other purposes.
Send options to hosts which ask for a DHCP lease.
See RFC 2132 for details of available options.
Common options can be given to dnsmasq by name:
run "dnsmasq --help dhcp" to get a list.
Note that all the common settings, such as netmask and broadcast address, DNS server and default route, are given sane defaults by dnsmasq.
You very likely will not need any dhcp-options. If you use Windows clients and Samba, there
# Override the default route supplied by dnsmasq, which assumes the # router is the same machine as the one running dnsmasq. # dhcp-option=3,184.108.40.206 # Do the same thing, but using the option name # dhcp-option=option:router,220.127.116.11 # Override the default route supplied by dnsmasq and send no default route at all # dhcp-option=3 #Set the NTP time server addresses # dhcp-option=option:ntp-server,192.168.0.4,10.10.0.5
Send DHCPv6 option.
Send DHCPv6 option for name-servers
Ask client to poll for option changes every six hours. (RFC4242)
Set option 58 client renewal time (T1).
Defaults to half of th lease time if not specified. (RFC2132)
Set option 59 rebinding time (T2).
Defaults to 7/8 of the lease time if not specified. (RFC2132)
Set the NTP time server address that of the machine running dnsmasq
Set the NIS domain name to "welly"
Set the default time-to-live to 50
Set the "all subnets are local" flag
Send the etherboot magic flag and then etherboot options (a string).
# dhcp-option=128,e4:45:74:68:00:00 # dhcp-option=129,NIC=eepro100
Specify an option which will only be sent to the "red" network
(see dhcp-range for the declaration of the "red" network)
Note that the tag: part must precede the option: part.
# dhcp-option = tag:red, option:ntp-server, 192.168.1.1
Send an empty WPAD option.
This may be requried to get windows 7 to behave.
Send RFC-3397 DNS domain search DHCP option.
Send RFC-3442 classless static routes (note the netmask encoding)
Send vendor-class specific options encapsulated in DHCP option 43.
The meaning of the options is defined by the vendor-class so options are sent only when the client supplied vendor class matches the class given here.
A substring match is OK, so "MSFT" matches "MSFT" and "MSFT 5.0".
This example sets the mtftp address to 0.0.0.0 for PXEClients.
Microsoft-specific option to tell Windows to release the lease when it shuts down.
Note the "i" flag, to tell dnsmasq to send the value as a four-byte integer - that's what microsoft wants. Note
Send the Encapsulated-vendor-class ID needed by some configurations of
Etherboot to allow is to recognise the DHCP server.
Send options to PXELinux. Note that we need to send the options even
though they don't appear in the parameter request list, so we need
to use dhcp-option-force here.
See http://syslinux.zytor.com/pxe.php#special for details.
Magic number - needed before anything else is recognised
# dhcp-option-force=208,f1:00:74:7e # Configuration file name #dhcp-option-force=209,configs/common # Path prefix #dhcp-option-force=210,/tftpboot/pxelinux/files/ # Reboot time. (Note 'i' to send 32-bit value) #dhcp-option-force=211,30i
Set the boot filename for netboot/PXE.
You will only need this is you want to boot machines over the network and you will need a TFTP server;
either dnsmasq's built in TFTP server or an external one. (See below for how to enable the TFTP server.)
# dhcp-boot=pxelinux.0 # use custom tftp-server in # dhcp-boot=pxelinux,server.name,192.168.1.100
Boot for Etherboot gPXE.
The idea is to send two different filenames, the first loads gPXE, and the second tells gPXE what to load.
The dhcp-match sets the gpxe tag for requests from gPXE.
#dhcp-match=set:gpxe,175 # gPXE sends a 175 option. #dhcp-boot=tag:!gpxe,undionly.kpxe #dhcp-boot=mybootimage # Encapsulated options for Etherboot gPXE. # All the options are encapsulated within option 175 #dhcp-option=encap:175, 1, 5b # priority code #dhcp-option=encap:175, 176, 1b # no-proxydhcp #dhcp-option=encap:175, 177, string # bus-id #dhcp-option=encap:175, 189, 1b # BIOS drive code #dhcp-option=encap:175, 190, user # iSCSI username #dhcp-option=encap:175, 191, pass # iSCSI password # Test for the architecture of a netboot client. # PXE clients are supposed to send their architecture as opt 93. (See RFC 4578) #dhcp-match=peecees, option:client-arch, 0 #x86-32 #dhcp-match=itanics, option:client-arch, 2 #IA64 #dhcp-match=hammers, option:client-arch, 6 #x86-64 #dhcp-match=mactels, option:client-arch, 7 #EFIx86-64
Do real PXE, rather than just booting a single file,
this is an alternative to dhcp-boot.
# pxe-prompt="What system shall I netboot?" # or with timeout before first available action is taken: # pxe-prompt="Press F8 for menu.", 60 # Available boot services. for PXE. # Boot from local disk # pxe-service=x86PC, "Boot from local disk" # Loads <tftp-root>/pxelinux.0 from dnsmasq TFTP server. # pxe-service=x86PC, "Install Linux", pxelinux # Loads <tftp-root>/pxelinux.0 from TFTP server at 18.104.22.168. # Beware this fails on old PXE ROMS. # pxe-service=x86PC, "Install Linux", pxelinux, 22.214.171.124 # Use bootserver on network, found by multicast or broadcast. # pxe-service=x86PC, "Install windows from RIS server", 1 #Use bootserver at a known IP address. # pxe-service=x86PC, "Install windows", 1, 126.96.36.199
Enable dnsmasq's built-in TFTP server
Set the root directory for files available via FTP.
# enable-tftp # tftp-root=/var/ftpd
Do not abort if the tftp-root is unavailable
Make the TFTP server more secure: with this set, only files owned by
the user dnsmasq is running as will be send over the net.
This option stops dnsmasq from negotiating a larger blocksize for TFTP transfers.
It will slow things down, but may rescue some broken TFTP clients.
Set the boot file name only when the "red" tag is set.
An example of dhcp-boot with an external TFTP server:
The name and IP address of the server are given after the filename.
Can fail with old PXE ROMS. Overridden by --pxe-service.
If there are multiple external tftp servers having a same name
(using /etc/hosts) then that name can be specified as the
tftp_servername (the third option to dhcp-boot) and in that
case dnsmasq resolves this name and returns the resultant IP
addresses in round robin fashion. This facility can be used to
load balance the tftp load among a set of servers.
Set the limit on DHCP leases, the default is 150
The DHCP server needs somewhere on disk to keep its lease database.
This defaults to a sane location, but if you want to change it, use
the line below.
Set the DHCP server to authoritative mode.
In this mode it will barge in and take over the lease for any client which broadcasts on the network, whether it has a record of the lease or not.
This avoids long timeoutS when a machine wakes up on a new network.
DO NOT enable this if there's the slightest chance that you might end up accidentally configuring a DHCP server for your campus/company unintentionally.
The ISC server uses
the same option, and this URL provides more information:
Run an executable when a DHCP lease is created or destroyed.
The arguments sent to the script are "add" or "del",
then the MAC address, the IP address and finally the hostname there is one.
Set the cachesize here.
If you want to disable negative caching, uncomment this.
Normally responses which come from /etc/hosts and the DHCP lease file have Time-To-Live set as zero, which conventionally means do not cache further.
If you are happy to trade lower load on the
server for potentially stale date, you can set a time-to-live (in seconds) here.
If you want dnsmasq to detect attempts by Verisign to send queries
to unregistered .com and .net hosts to its sitefinder service and
have dnsmasq instead return the correct NXDOMAIN response, uncomment
this line. You can add similar lines to do the same for other
registries which have implemented wildcard A records.
If you want to fix up DNS results from upstream servers, use the
alias option. This only works for IPv4.
This alias makes a result of 188.8.131.52 appear as 184.108.40.206
# alias=220.127.116.11,18.104.22.168 # and this maps 1.2.3.x to 5.6.7.x # alias=22.214.171.124,126.96.36.199,255.255.255.0 # and this maps 192.168.0.10->192.168.0.40 to 10.0.0.10->10.0.0.40 # alias=192.168.0.10-192.168.0.40,10.0.0.0,255.255.255.0
Change these lines if you want dnsmasq to serve MX records.
# Return an MX record named "maildomain.com" with target # servermachine.com and preference 50 # mx-host=maildomain.com,servermachine.com,50 # Set the default target for MX records created using the localmx option. # mx-target=servermachine.com # Return an MX record pointing to the mx-target for all local # machines. # localmx #Return an MX record pointing to itself for all local machines. # #selfmx
Change the following lines if you want dnsmasq to serve SRV
records. These are useful if you want to serve ldap requests for
Active Directory and other windows-originated DNS requests.
# See RFC 2782. # You may add multiple srv-host lines. # The fields are <name>,<target>,<port>,<priority>,<weight> # If the domain part if missing from the name (so that is just has the # service and protocol sections) then the domain given by the domain= # config option is used. (Note that expand-hosts does not need to be # set for this to work.) > A SRV record sending LDAP for the example.com domain to > ldapserver.example.com port 389 # srv-host=_ldap._tcp.example.com,ldapserver.example.com,389 > A SRV record sending LDAP for the example.com domain to > ldapserver.example.com port 389 (using domain=) # domain=example.com # srv-host=_ldap._tcp,ldapserver.example.com,389 > Two SRV records for LDAP, each with different priorities > # srv-host=_ldap._tcp.example.com,ldapserver.example.com,389,1 # srv-host=_ldap._tcp.example.com,ldapserver.example.com,389,2 > A SRV record indicating that there is no LDAP server for the domain > example.com # srv-host=_ldap._tcp.example.com
The following line shows how to make dnsmasq serve an arbitrary PTR
record. This is useful for DNS-SD. (Note that the
domain-name expansion done for SRV records _does_not
occur for PTR records.)
#ptr-record=_http._tcp.dns-sd-services,"New Employee Page._http._tcp.dns-sd-services" > Change the following lines to enable dnsmasq to serve TXT records. > These are used for things like SPF and zeroconf. (Note that the > domain-name expansion done for SRV records _does_not >occur for TXT records.) `` ### Example SPF. # txt-record=example.com,"v=spf1 a -all" ### Example zeroconf # txt-record=_http._tcp.example.com,name=value,paper=A4 ### Provide an alias for a "local" DNS name. Note that this _only_ works ### for targets which are names from DHCP or /etc/hosts. Give host # "bert" another name, bertrand
For debugging purposes, log each DNS query as it passes through
# dnsmasq. # log-queries
Log lots of extra information about DHCP transactions.
Include another lot of configuration options.
# conf-file=/etc/dnsmasq.more.conf # conf-dir=/etc/dnsmasq.d
Include all the files in a directory except those ending in .bak
Include all files in a directory which end in .conf
Include all files in /etc/dnsmasq and it should run except RPM backup files
dnsmasq \ conf-dir=/etc/dnsmas.d /etc/dnsmasq.d,\ .rpmnew,\ .rpmsave,\ .rpmorig