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DNSMASQ(8)							    DNSMASQ(8)

NAME
       dnsmasq - A lightweight DHCP and caching DNS server.

SYNOPSIS
       dnsmasq [OPTION]...

DESCRIPTION
       dnsmasq	is  a lightweight DNS, TFTP and DHCP server. It is intended to
       provide coupled DNS and DHCP service to a LAN.

       Dnsmasq accepts DNS queries and	either	answers	 them  from  a	small,
       local,  cache  or  forwards  them  to a real, recursive, DNS server. It
       loads the contents of /etc/hosts so that local hostnames which  do  not
       appear  in  the global DNS can be resolved and also answers DNS queries
       for DHCP configured hosts.

       The dnsmasq DHCP server supports static address assignments and	multi‐
       ple  networks.  It  automatically  sends a sensible default set of DHCP
       options, and can be configured to send any desired set of DHCP options,
       including vendor-encapsulated options. It includes a secure, read-only,
       TFTP server to allow net/PXE boot  of  DHCP  hosts  and	also  supports
       BOOTP.

       Dnsmasq supports IPv6 for DNS, but not DHCP.

OPTIONS
       Note  that  in  general	missing	 parameters are allowed and switch off
       functions, for instance "--pid-file" disables writing a	PID  file.  On
       BSD,  unless  the  GNU  getopt  library is linked, the long form of the
       options does not work on the command line; it is	 still	recognised  in
       the configuration file.

       --test Read and syntax check configuration file(s). Exit with code 0 if
	      all is OK, or a non-zero code otherwise. Do not  start  up  dns‐
	      masq.

       -h, --no-hosts
	      Don't read the hostnames in /etc/hosts.

       -H, --addn-hosts=<file>
	      Additional  hosts	 file.	Read  the  specified  file  as well as
	      /etc/hosts. If -h is given, read only the specified  file.  This
	      option  may be repeated for more than one additional hosts file.
	      If a directory is given, then read all the  files	 contained  in
	      that directory.

       -E, --expand-hosts
	      Add  the domain to simple names (without a period) in /etc/hosts
	      in the same way as for DHCP-derived names. Note that  this  does
	      not  apply  to  domain names in cnames, PTR records, TXT records
	      etc.

       -T, --local-ttl=<time>
	      When replying with  information  from  /etc/hosts	 or  the  DHCP
	      leases  file  dnsmasq  by default sets the time-to-live field to
	      zero, meaning that the requestor should  not  itself  cache  the
	      information. This is the correct thing to do in almost all situ‐
	      ations. This option allows a time-to-live	 (in  seconds)	to  be
	      given for these replies. This will reduce the load on the server
	      at the expense of clients using stale data  under	 some  circum‐
	      stances.

       --neg-ttl=<time>
	      Negative replies from upstream servers normally contain time-to-
	      live information in SOA records which dnsmasq uses for  caching.
	      If the replies from upstream servers omit this information, dns‐
	      masq does not cache the reply. This option gives a default value
	      for  time-to-live (in seconds) which dnsmasq uses to cache nega‐
	      tive replies even in the absence of an SOA record.

       -k, --keep-in-foreground
	      Do not go into the background at startup but  otherwise  run  as
	      normal.  This is intended for use when dnsmasq is run under dae‐
	      montools or launchd.

       -d, --no-daemon
	      Debug mode: don't fork to the  background,  don't	 write	a  pid
	      file,  don't  change  user id, generate a complete cache dump on
	      receipt on SIGUSR1, log to stderr as well as syslog, don't  fork
	      new processes to handle TCP queries.

       -q, --log-queries
	      Log the results of DNS queries handled by dnsmasq. Enable a full
	      cache dump on receipt of SIGUSR1.

       -8, --log-facility=<facility>
	      Set the facility to which dnsmasq will send syslog entries, this
	      defaults	to  DAEMON, and to LOCAL0 when debug mode is in opera‐
	      tion. If the facility given contains at least one '/' character,
	      it  is  taken  to	 be  a filename, and dnsmasq logs to the given
	      file, instead of syslog. (Errors	whilst	reading	 configuration
	      will  still  go  to  syslog,  but	 all  output from a successful
	      startup, and all output whilst running, will go  exclusively  to
	      the file.) When logging to a file, dnsmasq will close and reopen
	      the file when it receives SIGUSR2. This allows the log  file  to
	      be rotated without stopping dnsmasq.

       --log-async[=<lines>]
	      Enable  asynchronous logging and optionally set the limit on the
	      number of lines which will be queued by dnsmasq when writing  to
	      the syslog is slow.  Dnsmasq can log asynchronously: this allows
	      it to continue functioning without being blocked by syslog,  and
	      allows  syslog  to  use  dnsmasq for DNS queries without risking
	      deadlock.	 If the queue of log-lines becomes full, dnsmasq  will
	      log  the overflow, and the number of messages  lost. The default
	      queue length is 5, a sane value would be	5-25,  and  a  maximum
	      limit of 100 is imposed.

       -x, --pid-file=<path>
	      Specify  an  alternate path for dnsmasq to record its process-id
	      in. Normally /var/run/dnsmasq.pid.

       -u, --user=<username>
	      Specify the userid to which dnsmasq will change  after  startup.
	      Dnsmasq  must normally be started as root, but it will drop root
	      privileges after startup by changing id to  another  user.  Nor‐
	      mally  this  user	 is  "nobody" but that can be over-ridden with
	      this switch.

       -g, --group=<groupname>
	      Specify the group which dnsmasq will run	as.  The  defaults  to
	      "dip",	 if	available,    to    facilitate	  access    to
	      /etc/ppp/resolv.conf which is not normally world readable.

       -v, --version
	      Print the version number.

       -p, --port=<port>
	      Listen on <port> instead of the standard DNS port (53).  Setting
	      this to zero completely disables DNS function, leaving only DHCP
	      and/or TFTP.

       -P, --edns-packet-max=<size>
	      Specify the largest EDNS.0 UDP packet which is supported by  the
	      DNS  forwarder.  Defaults	 to  4096, which is the RFC5625-recom‐
	      mended size.

       -Q, --query-port=<query_port>
	      Send outbound DNS queries from, and listen for their replies on,
	      the  specific  UDP  port	<query_port>  instead  of using random
	      ports. NOTE that using this option will make dnsmasq less secure
	      against  DNS  spoofing attacks but it may be faster and use less
	      resources.  Setting this option to zero makes dnsmasq use a sin‐
	      gle  port allocated to it by the OS: this was the default behav‐
	      iour in versions prior to 2.43.

       --min-port=<port>
	      Do not use ports less than that given as source for outbound DNS
	      queries.	Dnsmasq	 picks	random	ports  as  source for outbound
	      queries: when this option is given, the ports used  will	always
	      to  larger  than that specified. Useful for systems behind fire‐
	      walls.

       -i, --interface=<interface name>
	      Listen only on the specified interface(s). Dnsmasq automatically
	      adds the loopback (local) interface to the list of interfaces to
	      use when the --interface option  is used. If no  --interface  or
	      --listen-address options are given dnsmasq listens on all avail‐
	      able interfaces except any given in --except-interface  options.
	      IP  alias	 interfaces (eg "eth1:0") cannot be used with --inter‐
	      face  or	--except-interface   options,	use   --listen-address
	      instead.

       -I, --except-interface=<interface name>
	      Do not listen on the specified interface. Note that the order of
	      --listen-address --interface and --except-interface options does
	      not  matter  and that --except-interface options always override
	      the others.

       -2, --no-dhcp-interface=<interface name>
	      Do not provide DHCP or TFTP on the specified interface,  but  do
	      provide DNS service.

       -a, --listen-address=<ipaddr>
	      Listen  on the given IP address(es). Both --interface and --lis‐
	      ten-address options may be given, in which case the set of  both
	      interfaces  and  addresses  is used. Note that if no --interface
	      option is given, but --listen-address is, dnsmasq will not auto‐
	      matically listen on the loopback interface. To achieve this, its
	      IP address, 127.0.0.1, must be explicitly given as  a  --listen-
	      address option.

       -z, --bind-interfaces
	      On systems which support it, dnsmasq binds the wildcard address,
	      even when it is listening on only some interfaces. It then  dis‐
	      cards  requests  that it shouldn't reply to. This has the advan‐
	      tage of working even when interfaces  come  and  go  and	change
	      address.	This  option  forces  dnsmasq  to really bind only the
	      interfaces it is listening on. About the only time when this  is
	      useful  is  when running another nameserver (or another instance
	      of dnsmasq) on  the  same	 machine.  Setting  this  option  also
	      enables multiple instances of dnsmasq which provide DHCP service
	      to run in the same machine.

       -y, --localise-queries
	      Return answers to DNS queries from /etc/hosts  which  depend  on
	      the  interface  over  which the query was received. If a name in
	      /etc/hosts has more than one address associated with it, and  at
	      least one of those addresses is on the same subnet as the inter‐
	      face  to	which  the  query  was	sent,  then  return  only  the
	      address(es)  on  that  subnet. This allows for a server  to have
	      multiple addresses in /etc/hosts corresponding to	 each  of  its
	      interfaces,  and	hosts  will  get  the correct address based on
	      which network they are attached to. Currently this  facility  is
	      limited to IPv4.

       -b, --bogus-priv
	      Bogus  private  reverse lookups. All reverse lookups for private
	      IP  ranges  (ie  192.168.x.x,  etc)  which  are  not  found   in
	      /etc/hosts  or  the  DHCP leases file are answered with "no such
	      domain" rather than being forwarded upstream.

       -V, --alias=[<old-ip>]|[<start-ip>-<end-ip>],<new-ip>[,<mask>]
	      Modify IPv4 addresses returned from upstream nameservers; old-ip
	      is  replaced  by	new-ip. If the optional mask is given then any
	      address which matches the masked old-ip will be re-written.  So,
	      for   instance  --alias=1.2.3.0,6.7.8.0,255.255.255.0  will  map
	      1.2.3.56 to 6.7.8.56 and 1.2.3.67	 to  6.7.8.67.	This  is  what
	      Cisco  PIX  routers call "DNS doctoring". If the old IP is given
	      as range, then only addresses in the range, rather than a	 whole
	      subnet,		   are		    re-written.		    So
	      --alias=192.168.0.10-192.168.0.40,10.0.0.0,255.255.255.0	  maps
	      192.168.0.10->192.168.0.40 to 10.0.0.10->10.0.0.40

       -B, --bogus-nxdomain=<ipaddr>
	      Transform	 replies  which	 contain the IP address given into "No
	      such domain" replies. This is intended to counteract  a  devious
	      move  made  by  Verisign	in  September  2003  when they started
	      returning the address of an advertising web page in response  to
	      queries  for unregistered names, instead of the correct NXDOMAIN
	      response. This option tells dnsmasq to fake the correct response
	      when  it	sees  this  behaviour.	As at Sept 2003 the IP address
	      being returned by Verisign is 64.94.110.11

       -f, --filterwin2k
	      Later versions of windows make periodic DNS requests which don't
	      get  sensible answers from the public DNS and can cause problems
	      by triggering dial-on-demand links. This flag turns on an option
	      to filter such requests. The requests blocked are for records of
	      types SOA and SRV, and type ANY where  the  requested  name  has
	      underscores, to catch LDAP requests.

       -r, --resolv-file=<file>
	      Read  the	 IP addresses of the upstream nameservers from <file>,
	      instead of /etc/resolv.conf. For the format  of  this  file  see
	      resolv.conf(5) the only lines relevant to dnsmasq are nameserver
	      ones. Dnsmasq can be told to  poll  more	than  one  resolv.conf
	      file, the first file name	 specified overrides the default, sub‐
	      sequent ones add to the list. This is only allowed when polling;
	      the  file with the currently latest modification time is the one
	      used.

       -R, --no-resolv
	      Don't read /etc/resolv.conf. Get upstream servers only from  the
	      command line or the dnsmasq configuration file.

       -1, --enable-dbus
	      Allow dnsmasq configuration to be updated via DBus method calls.
	      The configuration which can be changed is upstream  DNS  servers
	      (and  corresponding domains) and cache clear. Requires that dns‐
	      masq has been built with DBus support.

       -o, --strict-order
	      By default, dnsmasq will send queries to	any  of	 the  upstream
	      servers  it  knows  about	 and  tries to favour servers that are
	      known to be up. Setting this flag forces	dnsmasq	 to  try  each
	      query  with  each	 server	 strictly  in the order they appear in
	      /etc/resolv.conf

       --all-servers
	      By default, when dnsmasq	has  more  than	 one  upstream	server
	      available, it will send queries to just one server. Setting this
	      flag forces  dnsmasq  to	send  all  queries  to	all  available
	      servers.	The  reply from the server which answers first will be
	      returned to the original requestor.

       --stop-dns-rebind
	      Reject (and log) addresses from upstream nameservers  which  are
	      in  the private IP ranges. This blocks an attack where a browser
	      behind a firewall is used to probe machines on  the  local  net‐
	      work.

       -n, --no-poll
	      Don't poll /etc/resolv.conf for changes.

       --clear-on-reload
	      Whenever /etc/resolv.conf is re-read, clear the DNS cache.  This
	      is useful when new nameservers may have different data than that
	      held in cache.

       -D, --domain-needed
	      Tells  dnsmasq to never forward queries for plain names, without
	      dots or domain parts, to upstream nameservers. If	 the  name  is
	      not  known  from /etc/hosts or DHCP then a "not found" answer is
	      returned.

       -S,							      --local,
       --server=[/[<domain>]/[domain/]][<ipaddr>[#<port>][@<source-ip>|<inter‐
       face>[#<port>]]
	      Specify IP address of upstream servers  directly.	 Setting  this
	      flag does not suppress reading of /etc/resolv.conf, use -R to do
	      that. If one or more optional domains are given, that server  is
	      used  only for those domains and they are queried only using the
	      specified server. This is intended for private  nameservers:  if
	      you  have a nameserver on your network which deals with names of
	      the form xxx.internal.thekelleys.org.uk at 192.168.1.1 then giv‐
	      ing   the	 flag  -S /internal.thekelleys.org.uk/192.168.1.1 will
	      send all queries	for  internal  machines	 to  that  nameserver,
	      everything  else	will go to the servers in /etc/resolv.conf. An
	      empty domain  specification,  //	has  the  special  meaning  of
	      "unqualified  names  only"  ie names without any dots in them. A
	      non-standard port may be specified as part  of  the  IP  address
	      using  a	#  character.	More than one -S flag is allowed, with
	      repeated domain or ipaddr parts as required.

	      Also permitted is a -S flag which	 gives	a  domain  but	no  IP
	      address;	this  tells  dnsmasq that a domain is local and it may
	      answer queries from /etc/hosts or DHCP but should never  forward
	      queries on that domain to any upstream servers.  local is a syn‐
	      onym for server to make  configuration  files  clearer  in  this
	      case.

	      The  optional  string after the @ character tells dnsmasq how to
	      set the source of the queries to this nameserver. It  should  be
	      an  ip-address, which should belong to the machine on which dns‐
	      masq is running otherwise this server line will  be  logged  and
	      then  ignored,  or  an  interface	 name. If an interface name is
	      given, then queries to the server will be forced via that inter‐
	      face;  if	 an ip-address is given then the source address of the
	      queries will be set to that address.   The  query-port  flag  is
	      ignored  for  any	 servers which have a source address specified
	      but the port may be specified directly as	 part  of  the	source
	      address.	Forcing	 queries to an interface is not implemented on
	      all platforms supported by dnsmasq.

       -A, --address=/<domain>/[domain/]<ipaddr>
	      Specify an IP address to	return	for  any  host	in  the	 given
	      domains.	 Queries in the domains are never forwarded and always
	      replied to with the specified IP address which may  be  IPv4  or
	      IPv6.  To	 give  both  IPv4 and IPv6 addresses for a domain, use
	      repeated -A flags.  Note that /etc/hosts and DHCP	 leases	 over‐
	      ride this for individual names. A common use of this is to redi‐
	      rect the entire doubleclick.net domain to	 some  friendly	 local
	      web  server  to avoid banner ads. The domain specification works
	      in the same was as for --server, with  the  additional  facility
	      that  /#/	 matches  any  domain.	Thus --address=/#/1.2.3.4 will
	      always return 1.2.3.4 for any query not answered from /etc/hosts
	      or  DHCP	and  not sent to an upstream nameserver by a more spe‐
	      cific --server directive.

       -m, --mx-host=<mx name>[[,<hostname>],<preference>]
	      Return an MX record named <mx name> pointing to the given	 host‐
	      name (if given), or the host specified in the --mx-target switch
	      or, if that switch is not given, the host on  which  dnsmasq  is
	      running.	The  default is useful for directing mail from systems
	      on a LAN to a central server. The preference value is  optional,
	      and  defaults  to 1 if not given. More than one MX record may be
	      given for a host.

       -t, --mx-target=<hostname>
	      Specify the default target for the MX record  returned  by  dns‐
	      masq.  See  --mx-host.   If  --mx-target is given, but not --mx-
	      host, then dnsmasq returns a MX record containing the MX	target
	      for  MX  queries on the hostname of the machine on which dnsmasq
	      is running.

       -e, --selfmx
	      Return an MX record pointing to itself for each  local  machine.
	      Local machines are those in /etc/hosts or with DHCP leases.

       -L, --localmx
	      Return  an MX record pointing to the host given by mx-target (or
	      the machine on which dnsmasq is running) for each local machine.
	      Local machines are those in /etc/hosts or with DHCP leases.

       -W, --srv-host=<_service>.<_prot>.[<domain>],[<target>[,<port>[,<prior‐
       ity>[,<weight>]]]]
	      Return a SRV DNS record. See RFC2782 for details.	 If  not  sup‐
	      plied,  the  domain  defaults  to	 that  given by --domain.  The
	      default for the target domain is empty, and the default for port
	      is  one  and  the	 defaults for weight and priority are zero. Be
	      careful if transposing data from	BIND  zone  files:  the	 port,
	      weight  and priority numbers are in a different order. More than
	      one SRV record for a given service/domain is allowed,  all  that
	      match are returned.

       -Y, --txt-record=<name>[[,<text>],<text>]
	      Return  a	 TXT  DNS  record. The value of TXT record is a set of
	      strings, so  any number may be included, split by commas.

       --ptr-record=<name>[,<target>]
	      Return a PTR DNS record.

       --naptr-record=<name>,<order>,<preference>,<flags>,<service>,<reg‐
       exp>[,<replacement>]
	      Return an NAPTR DNS record, as specified in RFC3403.

       --cname=<cname>,<target>
	      Return  a	 CNAME	record	which indicates that <cname> is really
	      <target>. There are significant limitations on  the  target;  it
	      must be a DNS name which is known to dnsmasq from /etc/hosts (or
	      additional hosts files) or from DHCP. If	the  target  does  not
	      satisfy  this  criteria,	the  whole cname is ignored. The cname
	      must be unique, but it is permissable  to	 have  more  than  one
	      cname pointing to the same target.

       --interface-name=<name>,<interface>
	      Return  a	 DNS  record  associating  the	name  with the primary
	      address on the given interface. This flag specifies an A	record
	      for the given name in the same way as an /etc/hosts line, except
	      that the address is not  constant,  but  taken  from  the	 given
	      interface. If the interface is down, not configured or non-exis‐
	      tent, an empty record is returned. The matching  PTR  record  is
	      also  created,  mapping  the interface address to the name. More
	      than one name may be associated with  an	interface  address  by
	      repeating	 the flag; in that case the first instance is used for
	      the reverse address-to-name mapping.

       -c, --cache-size=<cachesize>
	      Set the size of dnsmasq's cache. The default is 150 names.  Set‐
	      ting the cache size to zero disables caching.

       -N, --no-negcache
	      Disable  negative	 caching.  Negative  caching allows dnsmasq to
	      remember "no such domain" answers from upstream nameservers  and
	      answer identical queries without forwarding them again.

       -0, --dns-forward-max=<queries>
	      Set  the	maximum	 number of concurrent DNS queries. The default
	      value is 150, which should be fine for  most  setups.  The  only
	      known  situation	where this needs to be increased is when using
	      web-server log file resolvers, which can generate large  numbers
	      of concurrent queries.

       -F,	--dhcp-range=[[net:]network-id,]<start-addr>,<end-addr>[,<net‐
       mask>[,<broadcast>]][,<lease time>]
	      Enable the DHCP server. Addresses will be	 given	out  from  the
	      range  <start-addr>  to  <end-addr>  and from statically defined
	      addresses given in dhcp-host  options.  If  the  lease  time  is
	      given,  then  leases  will be given for that length of time. The
	      lease time is in seconds, or minutes (eg 45m) or hours  (eg  1h)
	      or "infinite". If not given, the default lease time is one hour.
	      The minimum lease time  is  two  minutes.	 This  option  may  be
	      repeated,	 with  different  addresses, to enable DHCP service to
	      more than one network. For directly connected networks (ie, net‐
	      works on which the machine running dnsmasq has an interface) the
	      netmask is optional. It is, however, required for networks which
	      receive DHCP service via a relay agent. The broadcast address is
	      always optional. It is always allowed  to	 have  more  than  one
	      dhcp-range  in  a	 single	 subnet.  The optional network-id is a
	      alphanumeric label which marks this network so that dhcp options
	      may  be  specified  on a per-network basis.  When it is prefixed
	      with 'net:' then its meaning  changes  from  setting  a  tag  to
	      matching	it. Only one tag may be set, but more than one tag may
	      be matched.  The end address may	be  replaced  by  the  keyword
	      static which tells dnsmasq to enable DHCP for the network speci‐
	      fied, but not to dynamically allocate IP addresses:  only	 hosts
	      which   have  static  addresses  given  via  dhcp-host  or  from
	      /etc/ethers will be served. The end address may be  replaced  by
	      the  keyword proxy in which case dnsmasq will provide proxy-DHCP
	      on the specified subnet. (See  pxe-prompt	 and  pxe-service  for
	      details.)

       -G,							       --dhcp-
       host=[<hwaddr>][,id:<client_id>|*][,net:<netid>][,<ipaddr>][,<host‐
       name>][,<lease_time>][,ignore]
	      Specify  per  host parameters for the DHCP server. This allows a
	      machine with a particular hardware address to  be	 always	 allo‐
	      cated  the  same hostname, IP address and lease time. A hostname
	      specified like this overrides any supplied by the DHCP client on
	      the  machine. It is also allowable to ommit the hardware address
	      and include the hostname, in which case the IP address and lease
	      times  will apply to any machine claiming that name. For example
	      --dhcp-host=00:20:e0:3b:13:af,wap,infinite tells dnsmasq to give
	      the  machine  with  hardware  address 00:20:e0:3b:13:af the name
	      wap, and an infinite DHCP lease.	 --dhcp-host=lap,192.168.0.199
	      tells  dnsmasq to always allocate the machine lap the IP address
	      192.168.0.199. Addresses allocated like this are not constrained
	      to  be  in  the range given by the --dhcp-range option, but they
	      must be on the network being served by the DHCP  server.	It  is
	      allowed to use client identifiers rather than hardware addresses
	      to  identify  hosts  by  prefixing  with	'id:'.	Thus:  --dhcp-
	      host=id:01:02:03:04,.....	  refers to the host with client iden‐
	      tifier 01:02:03:04. It is also allowed to specify the client  ID
	      as text, like this: --dhcp-host=id:clientidastext,.....

	      The  special option id:* means "ignore any client-id and use MAC
	      addresses only." This is useful when a client presents a client-
	      id sometimes but not others.

	      If  a  name appears in /etc/hosts, the associated address can be
	      allocated to a DHCP lease, but  only  if	a  --dhcp-host	option
	      specifying  the  name  also exists. The special keyword "ignore"
	      tells dnsmasq to never offer a DHCP  lease  to  a	 machine.  The
	      machine can be specified by hardware address, client ID or host‐
	      name, for instance --dhcp-host=00:20:e0:3b:13:af,ignore This  is
	      useful  when  there  is another DHCP server on the network which
	      should be used by some machines.

	      The net:<network-id> sets the network-id tag whenever this dhcp-
	      host  directive  is in use. This can be used to selectively send
	      DHCP options just for this host. When a host matches  any	 dhcp-
	      host  directive (or one implied by /etc/ethers) then the special
	      network-id tag "known" is set. This allows dnsmasq to be config‐
	      ured  to	ignore	requests  from	unknown machines using --dhcp-
	      ignore=#known Ethernet addresses (but not client-ids)  may  have
	      wildcard	     bytes,	 so	 for	  example      --dhcp-
	      host=00:20:e0:3b:13:*,ignore will	 cause	dnsmasq	 to  ignore  a
	      range  of	 hardware addresses. Note that the "*" will need to be
	      escaped or quoted on a command line, but not in  the  configura‐
	      tion file.

	      Hardware addresses normally match any network (ARP) type, but it
	      is possible to restrict them to a single ARP type	 by  preceding
	      them   with   the	  ARP-type   (in  HEX)	and  "-".  so  --dhcp-
	      host=06-00:20:e0:3b:13:af,1.2.3.4 will only match	 a  Token-Ring
	      hardware	address,  since the ARP-address type for token ring is
	      6.

	      As a special case, it is possible to include more than one hard‐
	      ware		address.	      eg:	       --dhcp-
	      host=11:22:33:44:55:66,12:34:56:78:90:12,192.168.0.2 This allows
	      an IP address to be associated with multiple hardware addresses,
	      and gives dnsmasq permission to abandon a DHCP lease to  one  of
	      the hardware addresses when another one asks for a lease. Beware
	      that this is a dangerous thing to do, it will only work reliably
	      if  only one of the hardware addresses is active at any time and
	      there is no  way	for  dnsmasq  to  enforce  this.  It  is,  for
	      instance,	 useful	 to  allocate  a stable IP address to a laptop
	      which has both wired and wireless interfaces.

       --dhcp-hostsfile=<file>
	      Read DHCP host information from the  specified  file.  The  file
	      contains	information  about  one host per line. The format of a
	      line is the same as text to the right of '=' in --dhcp-host. The
	      advantage	 of storing DHCP host information in this file is that
	      it can be changed without re-starting dnsmasq: the file will  be
	      re-read when dnsmasq receives SIGHUP.

       --dhcp-optsfile=<file>
	      Read DHCP option information from the specified file. The advan‐
	      tage of using this option is the same as	for  --dhcp-hostsfile:
	      the  dhcp-optsfile will be re-read when dnsmasq receives SIGHUP.
	      Note that it is possible to encode the information in a  --dhcp-
	      boot  flag  as  DHCP  options, using the options names bootfile-
	      name, server-ip-address and tftp-server. This allows these to be
	      included in a dhcp-optsfile.

       -Z, --read-ethers
	      Read  /etc/ethers	 for  information  about  hosts	 for  the DHCP
	      server. The format of /etc/ethers is a  hardware	address,  fol‐
	      lowed  by either a hostname or dotted-quad IP address. When read
	      by dnsmasq these lines have exactly the same effect  as  --dhcp-
	      host options containing the same information. /etc/ethers is re-
	      read when dnsmasq receives SIGHUP.

       -O,	--dhcp-option=[<network-id>,[<network-id>,]][encap:<opt>,][vi-
       encap:<enterprise>,][vendor:[<vendor-class>],][<opt>|option:<opt-
       name>],[<value>[,<value>]]
	      Specify different or extra options to DHCP clients. By  default,
	      dnsmasq sends some standard options to DHCP clients, the netmask
	      and broadcast address are set to the same as  the	 host  running
	      dnsmasq,	and  the  DNS  server and default route are set to the
	      address of the machine  running  dnsmasq.	 If  the  domain  name
	      option  has  been	 set, that is sent.  This configuration allows
	      these defaults to be overridden, or other options specified. The
	      option,  to  be  sent  may  be  given  as a decimal number or as
	      "option:<option-name>"  The  option  numbers  are	 specified  in
	      RFC2132  and  subsequent	RFCs. The set of option-names known by
	      dnsmasq can be discovered by running "dnsmasq --help dhcp".  For
	      example,	to  set	 the  default  route option to 192.168.4.4, do
	      --dhcp-option=3,192.168.4.4 or  --dhcp-option  =	option:router,
	      192.168.4.4  and	to set the time-server address to 192.168.0.4,
	      do --dhcp-option = 42,192.168.0.4 or --dhcp-option = option:ntp-
	      server, 192.168.0.4 The special address 0.0.0.0 is taken to mean
	      "the address of the machine running dnsmasq". Data types allowed
	      are  comma separated dotted-quad IP addresses, a decimal number,
	      colon-separated hex digits and a text string.  If	 the  optional
	      network-ids are given then this option is only sent when all the
	      network-ids are matched.

	      Special processing is done on a text argument for option 119, to
	      conform with RFC 3397. Text or dotted-quad IP addresses as argu‐
	      ments to option 120 are handled as per RFC 3361. Dotted-quad  IP
	      addresses	 which are followed by a slash and then a netmask size
	      are encoded as described in RFC 3442.

	      Be careful: no checking is done that the correct	type  of  data
	      for  the option number is sent, it is quite possible to persuade
	      dnsmasq to generate illegal DHCP packets with injudicious use of
	      this  flag.  When	 the  value  is a decimal number, dnsmasq must
	      determine how large the data item is. It does this by  examining
	      the  option  number  and/or  the value, but can be overridden by
	      appending a single letter flag as follows: b = one byte, s = two
	      bytes,  i	 = four bytes. This is mainly useful with encapsulated
	      vendor class options (see below) where dnsmasq cannot  determine
	      data  size  from	the  option number. Option data which consists
	      solely of periods and digits will be interpreted by  dnsmasq  as
	      an  IP  address, and inserted into an option as such. To force a
	      literal string, use quotes. For instance when using option 66 to
	      send  a  literal IP address as TFTP server name, it is necessary
	      to do --dhcp-option=66,"1.2.3.4"

	      Encapsulated Vendor-class options may also  be  specified	 using
	      --dhcp-option:	 for	 instance    --dhcp-option=vendor:PXE‐
	      Client,1,0.0.0.0 sends the  encapsulated	vendor	class-specific
	      option  "mftp-address=0.0.0.0"  to any client whose vendor-class
	      matches "PXEClient".  The	 vendor-class  matching	 is  substring
	      based  (see  --dhcp-vendorclass  for details). If a vendor-class
	      option (number 60) is sent by dnsmasq, then  that	 is  used  for
	      selecting	 encapsulated options in preference to any sent by the
	      client. It is  possible  to  omit	 the  vendorclass  completely;
	      --dhcp-option=vendor:,1,0.0.0.0  in  which case the encapsulated
	      option is always sent.

	      Options may be encapsulated within other options:	 for  instance
	      --dhcp-option=encap:175,	190,  iscsi-client0  will  send option
	      175, within which is the option 190.  If	multiple  options  are
	      given  which  are	 encapsulated with the same option number then
	      they will be correctly combined into  one	 encapsulated  option.
	      encap:  and  vendor:  are	 may not both be set in the same dhcp-
	      option.

	      The final variant on encapsulated options is "Vendor-Identifying
	      Vendor  Options" as specified by RFC3925. These are denoted like
	      this: --dhcp-option=vi-encap:2, 10, text The number in  the  vi-
	      encap:  section  is  the IANA enterprise number used to identify
	      this option.

	      The address 0.0.0.0 is not  treated  specially  in  encapsulated
	      options.

       --dhcp-option-force=[<network-id>,[<network-id>,]][encap:<opt>,][vi-
       encap:<enterprise>,][vendor:[<vendor-class>],]<opt>,[<value>[,<value>]]
	      This works in exactly the same way as --dhcp-option except  that
	      the  option will always be sent, even if the client does not ask
	      for it in the parameter request list. This is sometimes  needed,
	      for example when sending options to PXELinux.

       --dhcp-no-override
	      Disable  re-use  of  the	DHCP servername and filename fields as
	      extra option space. If it can, dnsmasq moves the boot server and
	      filename	information  (from  dhcp-boot)	out of their dedicated
	      fields into DHCP options. This make extra space available in the
	      DHCP  packet  for options but can, rarely, confuse old or broken
	      clients. This flag forces "simple and safe" behaviour  to	 avoid
	      problems in such a case.

       -U, --dhcp-vendorclass=<network-id>,<vendor-class>
	      Map  from	 a  vendor-class string to a network id tag. Most DHCP
	      clients provide a	 "vendor  class"  which	 represents,  in  some
	      sense,  the  type	 of  host.  This option maps vendor classes to
	      tags, so that DHCP options may be selectively delivered to  dif‐
	      ferent  classes  of  hosts.  For example dhcp-vendorclass=print‐
	      ers,Hewlett-Packard JetDirect will allow options to be set  only
	      for  HP  printers	 like so: --dhcp-option=printers,3,192.168.4.4
	      The vendor-class string is substring matched against the vendor-
	      class supplied by the client, to allow fuzzy matching.

       -j, --dhcp-userclass=<network-id>,<user-class>
	      Map from a user-class string to a network id tag (with substring
	      matching, like vendor classes).  Most  DHCP  clients  provide  a
	      "user  class"  which  is	configurable.  This  option  maps user
	      classes to tags, so that DHCP options may be selectively	deliv‐
	      ered to different classes of hosts. It is possible, for instance
	      to use this to set a different printer server for hosts  in  the
	      class "accounts" than for hosts in the class "engineering".

       -4, --dhcp-mac=<network-id>,<MAC address>
	      Map  from a MAC address to a network-id tag. The MAC address may
	      include wildcards.  For  example	--dhcp-mac=3com,01:34:23:*:*:*
	      will  set	 the tag "3com" for any host whose MAC address matches
	      the pattern.

       --dhcp-circuitid=<network-id>,<circuit-id>,   --dhcp-remoteid=<network-
       id>,<remote-id>
	      Map  from	 RFC3046  relay agent options to network-id tags. This
	      data may be provided by DHCP relay  agents.  The	circuit-id  or
	      remote-id	 is normally given as colon-separated hex, but is also
	      allowed to be a simple string. If an  exact  match  is  achieved
	      between  the  circuit  or	 agent	ID and one provided by a relay
	      agent, the network-id tag is set.

       --dhcp-subscrid=<network-id>,<subscriber-id>
	      Map from RFC3993 subscriber-id relay agent options to network-id
	      tags.

       --dhcp-match=<network-id>,<option    number>|option:<option   name>|vi-
       encap:<enterprise>[,<value>]
	      Without a value, set the network-id tag if the  client  sends  a
	      DHCP  option of the given number or name. When a value is given,
	      set the tag only if the option is sent and  matches  the	value.
	      The  value  may  be  of  the form "01:ff:*:02" in which case the
	      value must match (apart from widcards) but the option  sent  may
	      have  unmatched  data  past  the end of the value. The value may
	      also be of the same form as in dhcp-option  in  which  case  the
	      option  sent is treated as an array, and one element must match,
	      so

	      --dhcp-match=efi-ia32,option:client-arch,6

	      will set the tag "efi-ia32" if the the number 6 appears  in  the
	      list  of architectures sent by the client in option 93. (See RFC
	      4578 for details.)  If the value is a string, substring matching
	      is used.

	      The   special  form  with	 vi-encap:<enterpise  number>  matches
	      against vendor-identifying  vendor  classes  for	the  specified
	      enterprise. Please see RFC 3925 for more details of the rare and
	      interesting beasts.

       -J, --dhcp-ignore=<network-id>[,<network-id>]
	      When all the given network-ids  match  the  set  of  network-ids
	      derived  from the net, host, vendor and user classes, ignore the
	      host and do not allocate it a DHCP lease.

       --dhcp-ignore-names[=<network-id>[,<network-id>]]
	      When all the given network-ids  match  the  set  of  network-ids
	      derived  from the net, host, vendor and user classes, ignore any
	      hostname provided by the host. Note that, unlike dhcp-ignore, it
	      is  permissible  to  supply  no  netid tags, in which case DHCP-
	      client supplied hostnames are always ignored, and DHCP hosts are
	      added  to	 the DNS using only dhcp-host configuration in dnsmasq
	      and the contents of /etc/hosts and /etc/ethers.

       --dhcp-broadcast=<network-id>[,<network-id>]
	      When all the given network-ids  match  the  set  of  network-ids
	      derived  from the net, host, vendor and user classes, always use
	      broadcast to communicate with the host when it is	 unconfigured.
	      Most  DHCP  clients  which  need broadcast replies set a flag in
	      their requests so that  this  happens  automatically,  some  old
	      BOOTP clients do not.

       -M,    --dhcp-boot=[net:<network-id>,]<filename>,[<servername>[,<server
       address>]]
	      Set BOOTP options to be returned by the DHCP server. Server name
	      and  address  are	 optional:  if	not provided, the name is left
	      empty, and the address set to the address of the machine running
	      dnsmasq.	If  dnsmasq is providing a TFTP service (see --enable-
	      tftp ) then only the filename is required here to enable network
	      booting.	 If  the  optional  network-id(s) are given, they must
	      match for this configuration to be sent. Note  that  network-ids
	      are prefixed by "net:" to distinguish them.

       --pxe-service=[net:<network-id>,]<CSA>,<menu   text>[,<basename>|<boot‐
       servicetype>][,<server address>]
	      Most uses of PXE boot-ROMS simply allow the PXE system to obtain
	      an  IP address and then download the file specified by dhcp-boot
	      and execute it. However the PXE system is capable of  more  com‐
	      plex functions when supported by a suitable DHCP server.

	      This  specifies  a  boot	option	which may appear in a PXE boot
	      menu. <CSA> is client system type, only services of the  correct
	      type  will  appear  in  a menu. The known types are x86PC, PC98,
	      IA64_EFI, Alpha, Arc_x86, Intel_Lean_Client,  IA32_EFI,  BC_EFI,
	      Xscale_EFI  and  X86-64_EFI;  an	integer	 may be used for other
	      types. The parameter after the menu text may be a file name,  in
	      which  case  dnsmasq  acts  as a boot server and directs the PXE
	      client to download the  file  by	TFTP,  either  from  itself  (
	      enable-tftp must be set for this to work) or another TFTP server
	      if the final IP address is given.	 Note that the "layer"	suffix
	      (normally	 ".0")	is supplied by PXE, and should not be added to
	      the basename. If an integer boot service	type,  rather  than  a
	      basename	is  given, then the PXE client will search for a suit‐
	      able boot service for that type on the network. This search  may
	      be done by broadcast, or direct to a server if its IP address is
	      provided.	 If no boot service type or filename is provided (or a
	      boot  service  type  of 0 is specified) then the menu entry will
	      abort the net boot procedure and	continue  booting  from	 local
	      media.

       --pxe-prompt=[net:<network-id>,]<prompt>[,<timeout>]
	      Setting  this  provides a prompt to be displayed after PXE boot.
	      If the timeout is given then after the timeout has elapsed  with
	      no keyboard input, the first available menu option will be auto‐
	      matically executed. If the timeout is zero then the first avail‐
	      able  menu  item	will be executed immediately. If pxe-prompt is
	      ommitted the system will wait for user input if there are multi‐
	      ple  items  in  the  menu, but boot immediately if there is only
	      one. See pxe-service for details of menu items.

	      Dnsmasq supports PXE "proxy-DHCP", in  this  case	 another  DHCP
	      server   on   the	 network  is  responsible  for	allocating  IP
	      addresses, and dnsmasq simply provides the information given  in
	      pxe-prompt  and  pxe-service  to	allow netbooting. This mode is
	      enabled using the proxy keyword in dhcp-range.

       -X, --dhcp-lease-max=<number>
	      Limits dnsmasq to the specified maximum number of	 DHCP  leases.
	      The  default  is	150. This limit is to prevent DoS attacks from
	      hosts which create thousands of leases and use lots of memory in
	      the dnsmasq process.

       -K, --dhcp-authoritative
	      Should be set when dnsmasq is definitely the only DHCP server on
	      a network.  It changes the behaviour from strict RFC  compliance
	      so  that	DHCP requests on unknown leases from unknown hosts are
	      not ignored. This allows new hosts to  get  a  lease  without  a
	      tedious  timeout under all circumstances. It also allows dnsmasq
	      to rebuild its lease database without  each  client  needing  to
	      reacquire a lease, if the database is lost.

       --dhcp-alternate-port[=<server port>[,<client port>]]
	      Change  the ports used for DHCP from the default. If this option
	      is given alone, without arguments, it changes the ports used for
	      DHCP  from  67  and 68 to 1067 and 1068. If a single argument is
	      given, that port number is used for the server and the port num‐
	      ber  plus	 one  used  for	 the client. Finally, two port numbers
	      allows arbitrary specification of both server and	 client	 ports
	      for DHCP.

       -3, --bootp-dynamic[=<network-id>[,<network-id>]]
	      Enable  dynamic allocation of IP addresses to BOOTP clients. Use
	      this with care, since each address allocated to a	 BOOTP	client
	      is leased forever, and therefore becomes permanently unavailable
	      for re-use by other hosts. if this is given without  tags,  then
	      it  unconditionally  enables dynamic allocation. With tags, only
	      when the tags are all set. It may be repeated with different tag
	      sets.

       -5, --no-ping
	      By  default,  the	 DHCP  server  will  attempt to ensure that an
	      address in not in use before allocating it to a  host.  It  does
	      this by sending an ICMP echo request (aka "ping") to the address
	      in question. If it gets a reply, then the address	 must  already
	      be  in use, and another is tried. This flag disables this check.
	      Use with caution.

       --log-dhcp
	      Extra logging for DHCP: log all the options sent to DHCP clients
	      and the netid tags used to determine them.

       -l, --dhcp-leasefile=<path>
	      Use the specified file to store DHCP lease information.

       -6 --dhcp-script=<path>
	      Whenever	a  new DHCP lease is created, or an old one destroyed,
	      the executable specified by this option is run. The arguments to
	      the  process  are	 "add", "old" or "del", the MAC address of the
	      host, the IP address, and the hostname, if known. "add" means  a
	      lease has been created, "del" means it has been destroyed, "old"
	      is a notification of an existing lease when dnsmasq starts or  a
	      change  to  MAC  address or hostname of an existing lease (also,
	      lease length or expiry and client-id, if leasefile-ro  is	 set).
	      If  the  MAC address is from a network type other than ethernet,
	      it    will    have    the	   network    type    prepended,    eg
	      "06-01:23:45:67:89:ab"  for  token  ring.	 The process is run as
	      root (assuming that dnsmasq was originally run as root) even  if
	      dnsmasq  is  configured  to  change UID to an unprivileged user.
	      The environment is inherited from the invoker of dnsmasq, and if
	      the host provided a client-id, this is stored in the environment
	      variable DNSMASQ_CLIENT_ID. If the fully-qualified  domain  name
	      of  the  host  is	 known,	 the  domain  part  is	stored in DNS‐
	      MASQ_DOMAIN.  If the client provides vendor-class,  hostname  or
	      user-class,
	       these   are   provided	in  DNSMASQ_VENDOR_CLASS  DNSMASQ_SUP‐
	      PLIED_HOSTNAME   and    DNSMASQ_USER_CLASS0..DNSMASQ_USER_CLASSn
	      variables,  but  only  for "add" actions or "old" actions when a
	      host resumes an existing lease, since these data are not held in
	      dnsmasq's lease database. If dnsmasq was compiled with HAVE_BRO‐
	      KEN_RTC, then the length of the lease (in seconds) is stored  in
	      DNSMASQ_LEASE_LENGTH,  otherwise	the  time  of  lease expiry is
	      stored in DNSMASQ_LEASE_EXPIRES. The  number  of	seconds	 until
	      lease  expiry  is always stored in DNSMASQ_TIME_REMAINING.  If a
	      lease used to have a hostname, which is removed, an "old"	 event
	      is  generated  with  the new state of the lease, ie no name, and
	      the former name is provided in  the  environment	variable  DNS‐
	      MASQ_OLD_HOSTNAME.  DNSMASQ_INTERFACE  stores  the  name	of the
	      interface on which the request arrived;  this  is	 not  set  for
	      "old"  actions  when  dnsmasq restarts. DNSMASQ_RELAY_ADDRESS is
	      set if the client used a DHCP relay to contact dnsmasq  and  the
	      IP  address of the relay is known. DNSMASQ_TAGS contains all the
	      network-id tags set during the DHCP  transaction,	 separated  by
	      spaces.	All  file  descriptors are closed except stdin, stdout
	      and stderr which are open to /dev/null (except in	 debug	mode).
	      The  script  is  not  invoked  concurrently: if subsequent lease
	      changes occur, the script is not invoked again until any	exist‐
	      ing  invocation  exits.  At  dnsmasq startup, the script will be
	      invoked for all existing leases as they are read from the	 lease
	      file.  Expired  leases will be called with "del" and others with
	      "old". <path> must be  an	 absolute  pathname,  no  PATH	search
	      occurs.  When  dnsmasq receives a HUP signal, the script will be
	      invoked for existing leases with an "old " event.

       --dhcp-scriptuser
	      Specify the user as which to run the lease-change	 script.  This
	      defaults	to root, but can be changed to another user using this
	      flag.

       -9, --leasefile-ro
	      Completely suppress use of the lease  database  file.  The  file
	      will not be created, read, or written. Change the way the lease-
	      change script (if one is provided) is called, so that the	 lease
	      database may be maintained in external storage by the script. In
	      addition to the invocations  given in --dhcp-script  the	lease-
	      change  script is called once, at dnsmasq startup, with the sin‐
	      gle argument "init". When called like  this  the	script	should
	      write  the  saved state of the lease database, in dnsmasq lease‐
	      file format, to stdout and exit with  zero  exit	code.  Setting
	      this  option  also forces the leasechange script to be called on
	      changes to the client-id and lease length and expiry time.

       --bridge-interface=<interface>,<alias>[,<alias>]
	      Treat DHCP request packets arriving at any of the <alias> inter‐
	      faces as if they had arrived at <interface>. This option is nec‐
	      essary when using "old style" bridging on BSD  platforms,	 since
	      packets arrive at tap interfaces which don't have an IP address.

       -s, --domain=<domain>[,<address range>]
	      Specifies	 DNS  domains  for  the DHCP server. Domains may be be
	      given unconditionally (without the IP range) or for  limited  IP
	      ranges.  This has two effects; firstly it causes the DHCP server
	      to return the domain to any hosts which request it, and secondly
	      it  sets	the domain which it is legal for DHCP-configured hosts
	      to claim. The intention is to constrain  hostnames  so  that  an
	      untrusted	 host on the LAN cannot advertise its name via dhcp as
	      e.g. "microsoft.com" and capture traffic not meant for it. If no
	      domain suffix is specified, then any DHCP hostname with a domain
	      part (ie with a period) will be disallowed and logged. If suffix
	      is  specified,  then  hostnames  with a domain part are allowed,
	      provided the domain part matches the suffix. In addition, when a
	      suffix is set then hostnames without a domain part have the suf‐
	      fix added as an optional domain part. Eg on my network I can set
	      --domain=thekelleys.org.uk  and  have a machine whose DHCP host‐
	      name is "laptop". The IP address for that machine	 is  available
	      from dnsmasq both as "laptop" and "laptop.thekelleys.org.uk". If
	      the domain is given as "#" then the  domain  is  read  from  the
	      first  "search"  directive  in /etc/resolv.conf (or equivalent).
	      The address range can be of the form <ip	address>,<ip  address>
	      or  <ip  address>/<netmask>  or  just a single <ip address>. See
	      --dhcp-fqdn which can  change  the  behaviour  of	 dnsmasq  with
	      domains.

       --dhcp-fqdn
	      In  the  default	mode, dnsmasq inserts the unqualified names of
	      DHCP clients into the DNS. For this reason, the  names  must  be
	      unique, even if two clients which have the same name are in dif‐
	      ferent domains. If a second DHCP client appears  which  has  the
	      same  name  as an existing client, the name is transfered to the
	      new client. If --dhcp-fqdn is set, this behaviour	 changes:  the
	      unqualified name is no longer put in the DNS, only the qualified
	      name. Two DHCP clients with the same  name  may  both  keep  the
	      name,  provided  that the domain part is different (ie the fully
	      qualified names differ.) To ensure that all names have a	domain
	      part,  there must be at least --domain without an address speci‐
	      fied when --dhcp-fqdn is set.

       --enable-tftp
	      Enable the TFTP server function. This is deliberately limited to
	      that  needed  to net-boot a client. Only reading is allowed; the
	      tsize and blksize extensions are supported (tsize is  only  sup‐
	      ported in octet mode).

       --tftp-root=<directory>
	      Look  for	 files	to  transfer  using TFTP relative to the given
	      directory. When this is set, TFTP paths which include  ".."  are
	      rejected,	 to  stop  clients getting outside the specified root.
	      Absolute paths (starting with /) are allowed, but they  must  be
	      within the tftp-root.

       --tftp-unique-root
	      Add the IP address of the TFTP client as a path component on the
	      end of the TFTP-root  (in	 standard  dotted-quad	format).  Only
	      valid  if	 a  tftp-root  is  set	and  the directory exists. For
	      instance, if tftp-root is "/tftp" and  client  1.2.3.4  requests
	      file    "myfile"	  then	  the	 effective    path   will   be
	      "/tftp/1.2.3.4/myfile" if /tftp/1.2.3.4 exists  or  /tftp/myfile
	      otherwise.

       --tftp-secure
	      Enable  TFTP  secure mode: without this, any file which is read‐
	      able by the dnsmasq process  under  normal  unix	access-control
	      rules  is	 available  via	 TFTP.	When the --tftp-secure flag is
	      given, only files owned by the user running the dnsmasq  process
	      are accessible. If dnsmasq is being run as root, different rules
	      apply: --tftp-secure has no effect, but only  files  which  have
	      the world-readable bit set are accessible. It is not recommended
	      to run dnsmasq as root with  TFTP	 enabled,  and	certainly  not
	      without  specifying  --tftp-root. Doing so can expose any world-
	      readable file on the server to any host on the net.

       --tftp-max=<connections>
	      Set the maximum number of concurrent TFTP	 connections  allowed.
	      This defaults to 50. When serving a large number of TFTP connec‐
	      tions, per-process file descriptor limits	 may  be  encountered.
	      Dnsmasq  needs one file descriptor for each concurrent TFTP con‐
	      nection and one file descriptor per unique file (plus a few oth‐
	      ers).  So serving the same file simultaneously to n clients will
	      use require about n + 10	file  descriptors,  serving  different
	      files  simultaneously to n clients will require about (2*n) + 10
	      descriptors. If --tftp-port-range is given, that can affect  the
	      number of concurrent connections.

       --tftp-no-blocksize
	      Stop  the	 TFTP  server  from negotiating the "blocksize" option
	      with a client. Some buggy clients request this option  but  then
	      behave badly when it is granted.

       --tftp-port-range=<start>,<end>
	      A	 TFTP  server listens on a well-known port (69) for connection
	      initiation, but it also uses a  dynamically-allocated  port  for
	      each  connection.	 Normally  these  are allocated by the OS, but
	      this option specifies a range of ports for use  by  TFTP	trans‐
	      fers.  This  can be useful when TFTP has to traverse a firewall.
	      The start of the range cannot be lower than 1025 unless  dnsmasq
	      is running as root. The number of concurrent TFTP connections is
	      limited by the size of the port range.

       -C, --conf-file=<file>
	      Specify a different configuration file. The conf-file option  is
	      also allowed in configuration files, to include multiple config‐
	      uration files.

       -7, --conf-dir=<directory>[,<file-extension>......]
	      Read all the files  in  the  given  directory  as	 configuration
	      files.  If  extension(s) are given, any files which end in those
	      extensions are skipped. Any files whose names end in ~ or	 start
	      with . or start and end with # are always skipped. This flag may
	      be given on the command line or in a configuration file.

CONFIG FILE
       At startup, dnsmasq reads /etc/dnsmasq.conf, if it exists. (On FreeBSD,
       the  file  is  /usr/local/etc/dnsmasq.conf  )  (but  see	 the -C and -7
       options.) The format of this file consists  of  one  option  per	 line,
       exactly as the long options detailed in the OPTIONS section but without
       the leading "--". Lines starting with # are comments and	 ignored.  For
       options	which may only be specified once, the configuration file over‐
       rides the command line.	Quoting is allowed in a config file: between "
       quotes  the special meanings of ,:. and # are removed and the following
       escapes are allowed: \\ \" \t \e \b \r and \n. The later	 corresponding
       to tab, escape, backspace, return and newline.

NOTES
       When  it	 receives a SIGHUP, dnsmasq clears its cache and then re-loads
       /etc/hosts and /etc/ethers and  any  file  given	 by  --dhcp-hostsfile,
       --dhcp-optsfile	or  --addn-hosts.   The	 dhcp  lease  change script is
       called for all existing DHCP leases. If --no-poll is  set  SIGHUP  also
       re-reads	 /etc/resolv.conf.   SIGHUP does NOT re-read the configuration
       file.

       When it receives a SIGUSR1, dnsmasq writes  statistics  to  the	system
       log.  It	 writes	 the cache size, the number of names which have had to
       removed from the cache before they expired in order to  make  room  for
       new  names  and	the total number of names that have been inserted into
       the cache. For each upstream server it  gives  the  number  of  queries
       sent, and the number which resulted in an error. In --no-daemon mode or
       when full logging is enabled (-q), a complete dump of the  contents  of
       the cache is made.

       When it receives SIGUSR2 and it is logging direct to a file (see --log-
       facility ) dnsmasq will close and reopen the log file. Note that during
       this operation, dnsmasq will not be running as root. When it first cre‐
       ates the logfile dnsmasq changes the ownership of the file to the  non-
       root  user  it  will run as. Logrotate should be configured to create a
       new log file with the ownership which matches the existing  one	before
       sending	SIGUSR2.   If TCP DNS queries are in progress, the old logfile
       will remain open in child processes which are handling TCP queries  and
       may  continue  to  be  written.	There is a limit of 150 seconds, after
       which all existing TCP processes will have expired: for this reason, it
       is  not	wise  to configure logfile compression for logfiles which have
       just been rotated. Using logrotate, the required options are create and
       delaycompress.

       Dnsmasq	is  a  DNS  query  forwarder: it it not capable of recursively
       answering arbitrary queries starting from the root servers but forwards
       such  queries  to  a fully recursive upstream DNS server which is typi‐
       cally provided by an ISP. By default, dnsmasq reads /etc/resolv.conf to
       discover	 the  IP  addresses of the upstream nameservers it should use,
       since the information is typically stored there.	 Unless	 --no-poll  is
       used,  dnsmasq  checks  the  modification  time of /etc/resolv.conf (or
       equivalent if --resolv-file is used) and re-reads  it  if  it  changes.
       This  allows the DNS servers to be set dynamically by PPP or DHCP since
       both protocols provide the information.	Absence of /etc/resolv.conf is
       not an error since it may not have been created before a PPP connection
       exists. Dnsmasq simply keeps checking in case /etc/resolv.conf is  cre‐
       ated  at	 any  time.  Dnsmasq  can  be  told  to	 parse	more  than one
       resolv.conf file. This is useful on a laptop, where both PPP  and  DHCP
       may  be	used: dnsmasq can be set to poll both /etc/ppp/resolv.conf and
       /etc/dhcpc/resolv.conf and will use the contents of  whichever  changed
       last, giving automatic switching between DNS servers.

       Upstream	 servers  may  also be specified on the command line or in the
       configuration file.  These  server  specifications  optionally  take  a
       domain  name  which tells dnsmasq to use that server only to find names
       in that particular domain.

       In order to configure dnsmasq to act as cache for the host on which  it
       is  running,  put  "nameserver  127.0.0.1" in /etc/resolv.conf to force
       local processes to send queries to dnsmasq.  Then  either  specify  the
       upstream	 servers  directly  to	dnsmasq	 using --server options or put
       their addresses real in another file, say /etc/resolv.dnsmasq  and  run
       dnsmasq	with  the -r /etc/resolv.dnsmasq option. This second technique
       allows for dynamic update of the server addresses by PPP or DHCP.

       Addresses in /etc/hosts will "shadow" different addresses for the  same
       names  in  the  upstream	 DNS, so "mycompany.com 1.2.3.4" in /etc/hosts
       will ensure that queries for "mycompany.com" always return 1.2.3.4 even
       if  queries  in	the  upstream  DNS  would otherwise return a different
       address. There is one exception to this: if the upstream DNS contains a
       CNAME  which  points  to	 a  shadowed  name,  then looking up the CNAME
       through dnsmasq will result in the unshadowed address  associated  with
       the  target  of	the  CNAME.  To	 work  around  this,  add the CNAME to
       /etc/hosts so that the CNAME is shadowed too.

       The network-id system works as follows: For each DHCP request,  dnsmasq
       collects	 a  set of valid network-id tags, one from the dhcp-range used
       to allocate the address, one from any matching dhcp-host	 (and  "known"
       if a dhcp-host matches) the tag "bootp" for BOOTP requests, a tag whose
       name is the name if the interface on which  the	request	 arrived,  and
       possibly many from matching vendor classes and user classes sent by the
       DHCP client. Any dhcp-option which has network-id tags will be used  in
       preference   to	an  untagged dhcp-option, provided that _all_ the tags
       match somewhere in the set collected as described above. The prefix '#'
       on  a  tag  means  'not'	 so  --dhcp=option=#purple,3,1.2.3.4 sends the
       option when the network-id tag purple is not in the set of valid tags.

       If the network-id in a dhcp-range is  prefixed  with  'net:'  then  its
       meaning	changes	 from  setting	a tag to matching it. Thus if there is
       more than dhcp-range on a subnet, and one is tagged with	 a  network-id
       which  is set (for instance from a vendorclass option) then hosts which
       set the netid tag will be allocated addresses in the tagged range.

       The DHCP server in dnsmasq will function as a BOOTP server  also,  pro‐
       vided that the MAC address and IP address for clients are given, either
       using dhcp-host configurations or in /etc/ethers	 ,  and	 a  dhcp-range
       configuration  option  is present to activate the DHCP server on a par‐
       ticular network. (Setting --bootp-dynamic removes the need  for	static
       address mappings.) The filename parameter in a BOOTP request is matched
       against netids in dhcp-option configurations, as is  the	 tag  "bootp",
       allowing some control over the options returned to different classes of
       hosts.

EXIT CODES
       0 - Dnsmasq successfully forked into the background, or terminated nor‐
       mally if backgrounding is not enabled.

       1 - A problem with configuration was detected.

       2  - A problem with network access occurred (address in use, attempt to
       use privileged ports without permission).

       3 - A problem occurred with a filesystem operation (missing file/direc‐
       tory, permissions).

       4 - Memory allocation failure.

       5 - Other miscellaneous problem.

       11  or  greater	-  a non zero return code was received from the lease-
       script process "init" call. The exit code from dnsmasq is the  script's
       exit code with 10 added.

LIMITS
       The default values for resource limits in dnsmasq are generally conser‐
       vative, and appropriate for embedded router type devices with slow pro‐
       cessors and limited memory. On more capable hardware, it is possible to
       increase the limits,  and  handle  many	more  clients.	The  following
       applies to dnsmasq-2.37: earlier versions did not scale as well.

       Dnsmasq	is  capable  of	 handling DNS and DHCP for at least a thousand
       clients. Clearly to do this  the	 value	of  --dhcp-lease-max  must  be
       increased,  and	lease  times  should  not be very short (less than one
       hour). The value of --dns-forward-max can be increased: start  with  it
       equal  to  the  number  of clients and increase if DNS seems slow. Note
       that DNS performance depends too on the	performance  of	 the  upstream
       nameservers. The size of the DNS cache may be increased: the hard limit
       is 10000 names and the default (150) is very low.  Sending  SIGUSR1  to
       dnsmasq	makes  it log information which is useful for tuning the cache
       size. See the NOTES section for details.

       The built-in TFTP server is capable of many  simultaneous  file	trans‐
       fers:  the  absolute  limit  is	related	 to the number of file-handles
       allowed to a process and the ability of the  select()  system  call  to
       cope  with  large numbers of file handles. If the limit is set too high
       using --tftp-max it will be scaled down and the actual limit logged  at
       start-up.  Note	that more transfers are possible when the same file is
       being sent than when each transfer sends a different file.

       It is possible to use dnsmasq to block Web advertising by using a  list
       of  known  banner-ad servers, all resolving to 127.0.0.1 or 0.0.0.0, in
       /etc/hosts or an additional hosts file. The list can be very long, dns‐
       masq  has  been	tested	successfully with one million names. That size
       file needs a 1GHz processor and about 60Mb of RAM.

INTERNATIONALISATION
       Dnsmasq can be compiled to support internationalisation.	 To  do	 this,
       the  make  targets "all-i18n" and "install-i18n" should be used instead
       of the standard targets "all" and "install". When  internationalisation
       is compiled in, dnsmasq will produce log messages in the local language
       and support internationalised  domain  names  (IDN).  Domain  names  in
       /etc/hosts,  /etc/ethers	 and /etc/dnsmasq.conf which contain non-ASCII
       characters will be translated to the DNS-internal punycode  representa‐
       tion.  Note  that dnsmasq determines both the language for messages and
       the assumed charset for configuration files from the  LANG  environment
       variable.  This should be set to the system default value by the script
       which is responsible for starting dnsmasq. When editing the  configura‐
       tion  files,  be	 careful to do so using only the system-default locale
       and not user-specific one, since dnsmasq has no direct way of determin‐
       ing the charset in use, and must assume that it is the system default.

FILES
       /etc/dnsmasq.conf

       /usr/local/etc/dnsmasq.conf

       /etc/resolv.conf

       /etc/hosts

       /etc/ethers

       /var/lib/misc/dnsmasq.leases

       /var/db/dnsmasq.leases

       /var/run/dnsmasq.pid

SEE ALSO
       hosts(5), resolver(5)

AUTHOR
       This manual page was written by Simon Kelley <simon@thekelleys.org.uk>.

								    DNSMASQ(8)
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