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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 multiple 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 dnsmasq.

       -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 situations. 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 circumstances.

       --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, dnsmasq does not cache the reply. This
              option gives a default value for time-to-live (in seconds) which dnsmasq uses to cache negative  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 daemontools 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 operation. If the facility given contains at least one '/' character, it is taken to be a filename, and dns-
              masq  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  log-
              ging  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 with-
              out 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. Normally 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-recommended 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 single port allocated to it
              by the OS: this was the default behaviour 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 firewalls.

       -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 available interfaces except any given in --except-interface options.  IP  alias  interfaces
              (eg "eth1:0") cannot be used with --interface 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-inter-
              face 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 --listen-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 automatically 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 inter-
              faces. It then discards requests that it shouldn't reply to. This has the advantage of working  even  when  inter-
              faces  come and go and change address. This option forces dnsmasq to really bind only the interfaces it is listen-
              ing on. About the only time when this is useful is when running another nameserver (or another  instance  of  dns-
              masq)  on the same machine. Setting this option also enables multiple instances of dnsmasq which provide DHCP ser-
              vice 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 interface 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, subsequent 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 dnsmasq 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 network.

       -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>|<interface>[#<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 giving  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 synonym 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 dnsmasq 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 interface; 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 override this for individual  names.  A
              common  use  of  this  is to redirect 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 specific --server directive.

       -m, --mx-host=<mx name>[[,<hostname>],<preference>]
              Return an MX record named <mx name> pointing to the given hostname (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 dnsmasq. 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>[,<priority>[,<weight>]]]]
              Return  a SRV DNS record. See RFC2782 for details. If not supplied, 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 prior-
              ity  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>,<regexp>[,<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 per-
              missable 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-existent,  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. Setting 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 name-
              servers 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>[,<netmask>[,<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 dif-
              ferent addresses, to enable DHCP service to more than one network. For directly connected networks  (ie,  networks
              on  which the machine running dnsmasq has an interface) the netmask is optional. It is, however, required for net-
              works 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
              specified,  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  dns-
              masq 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>][,<hostname>][,<lease_time>][,ignore]
              Specify  per  host  parameters for the DHCP server. This allows a machine with a particular hardware address to be
              always allocated the same hostname, IP address and lease time. A hostname specified like this overrides  any  sup-
              plied  by the DHCP client on the machine. It is also allowable to ommit the hardware address and include the host-
              name, 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 identifier 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 hostname, 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  configured  to  ignore
              requests  from  unknown machines using --dhcp-ignore=#known Ethernet addresses (but not client-ids) may have wild-
              card 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 configuration
              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   hardware   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 infor-
              mation  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 advantage 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,
              followed 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 arguments 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 deci-
              mal 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  deter-
              mine  data  size  from  the  option number. Option data which consists solely of periods and digits will be inter-
              preted 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=ven-
              dor:PXEClient,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 enter-
              prise 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 different classes of hosts.  For  example  dhcp-vendorclass=printers,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 delivered 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  cir-
              cuit-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 speci-
              fied 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>|<bootservicetype>][,<server address>]
              Most  uses  of PXE boot-ROMS simply allow the PXE system to obtain an IP address and then download the file speci-
              fied by dhcp-boot and execute it. However the PXE system is capable of more complex 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 param-
              eter 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 suitable 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 automatically executed. If the timeout  is
              zero  then  the  first available menu item will be executed immediately. If pxe-prompt is ommitted the system will
              wait for user input if there are multiple 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 number plus one used for the client. Finally, two port numbers allows arbitrary specifica-
              tion 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 DNSMASQ_DOMAIN.  If the client provides vendor-class, hostname or user-class,
               these are provided in DNSMASQ_VENDOR_CLASS DNSMASQ_SUPPLIED_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_BROKEN_RTC, then the length of  the  lease
              (in  seconds)  is  stored  in  DNSMASQ_LEASE_LENGTH,  otherwise  the  time  of  lease  expiry  is  stored  in DNS-
              MASQ_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  DNSMASQ_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 existing 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 single argument "init". When called like this the script should write the saved
              state of the lease database, in dnsmasq leasefile 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> interfaces as if they had arrived at  <interface>.  This
              option is necessary 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 host-
              names  without  a  domain  part  have  the  suffix  added  as  an optional domain part. Eg on my network I can set
              --domain=thekelleys.org.uk and have a machine whose DHCP hostname 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 different 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 with-
              out an address specified 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 supported 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 readable 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-read-
              able 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 connections, per-process file descriptor limits may be encountered. Dnsmasq needs  one  file  descriptor  for
              each  concurrent  TFTP connection and one file descriptor per unique file (plus a few others). So serving the same
              file simultaneously to n clients will use require about n + 10 file descriptors, serving different files  simulta-
              neously 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-allo-
              cated port for each connection. Normally these are allocated by the OS, but this option specifies a range of ports
              for  use by TFTP transfers. 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 configuration 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 overrides 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 num-
       ber 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  creates  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  con-
       figure  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 typically 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  created
       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  con-
       tents 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 associ-
       ated 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 net-
       work-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, provided 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 particular 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 normally 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/directory, 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 conservative, and appropriate for embedded router type
       devices with slow processors 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 perfor-
       mance 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 use-
       ful for tuning the cache size. See the NOTES section for details.


       The built-in TFTP server is capable of many simultaneous file transfers: 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, dnsmasq has been tested  suc-
       cessfully 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 representation. Note that dnsmasq determines both the language for messages and the assumed charset for configu-
       ration 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 configuration files, be careful to do so using only the system-default
       locale and not user-specific one, since dnsmasq has no direct way of determining 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/dnsmasq/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 <simonATthekelleys.uk>.





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