Provided by: dhcp_2.0pl5-19.4_i386 bug

NAME

       dhcp-options - Dynamic Host Configuration Protocol options

DESCRIPTION

       The  Dynamic  Host  Configuration protocol allows the client to receive
       options from the DHCP server describing the network  configuration  and
       various  services that are available on the network.   When configuring
       dhcpd(8) or dhclient(8) , options must often be declared.   The  syntax
       for  declaring  options,  and the names and formats of the options that
       can be declared, are documented here.

REFERENCE: OPTION STATEMENTS

       DHCP option statements always start with the option  keyword,  followed
       by  an option name, followed by option data.  The option names and data
       formats are described below.   It  is  not  necessary  to  exhaustively
       specify  all  DHCP  options  -  only  those options which are needed by
       clients must be specified.

       Option data comes in a variety of formats, as defined below:

       The ip-address data type can  be  entered  either  as  an  explicit  IP
       address   (e.g.,   239.254.197.10)   or   as   a   domain  name  (e.g.,
       haagen.isc.org).  When entering a domain name, be sure that that domain
       name resolves to a single IP address.

       The  int32  data  type  specifies a signed 32-bit integer.   The uint32
       data type specifies an unsigned 32-bit integer.   The int16 and  uint16
       data  types specify signed and unsigned 16-bit integers.   The int8 and
       uint8 data types specify signed and unsigned 8-bit integers.   Unsigned
       8-bit integers are also sometimes referred to as octets.

       The  string  data  type  specifies  an  NVT ASCII string, which must be
       enclosed in double quotes -  for  example,  to  specify  a  domain-name
       option, the syntax would be

            option domain-name "isc.org";

       The  flag data type specifies a boolean value.   Booleans can be either
       true or false (or on or off, if that makes more sense to you).

       The data-string data type specifies either an NVT ASCII string enclosed
       in  double  quotes,  or  a  series  of octets specified in hexadecimal,
       separated by colons.   For example:

            option dhcp-client-identifier "CLIENT-FOO";
       or
            option dhcp-client-identifier 43:4c:49:45:54:2d:46:4f:4f;

       The documentation for the various options mentioned below is taken from
       the latest IETF draft document on DHCP options.   Options which are not
       listed by name may be defined by the name option-nnn, where nnn is  the
       decimal  number  of  the  option  code.   These options may be followed
       either by a string, enclosed in quotes,  or  by  a  series  of  octets,
       expressed  as  two-digit hexadecimal numbers separated by colons.   For
       example:

            option option-133 "my-option-133-text";
            option option-129 1:54:c9:2b:47;

       Because dhcpd does not know the format of these undefined option codes,
       no checking is done to ensure the correctness of the entered data.

       The standard options are:

       option subnet-mask ip-address;

          The subnet mask option specifies the client’s subnet mask as per RFC
          950.  If no subnet mask option is provided anywhere in scope,  as  a
          last  resort  dhcpd  will  use  the  subnet  mask  from  the  subnet
          declaration for the network on which an address is  being  assigned.
          However, any subnet-mask option declaration that is in scope for the
          address being assigned will override the subnet  mask  specified  in
          the subnet declaration.

       option time-offset int32;

          The  time-offset  option specifies the offset of the client’s subnet
          in seconds from Coordinated Universal Time (UTC).

       option routers ip-address [, ip-address...  ];

          The routers option specifies a list of IP addresses for  routers  on
          the   client’s  subnet.   Routers  should  be  listed  in  order  of
          preference.

       option time-servers ip-address [, ip-address...  ];

          The time-server option specifies a list  of  RFC  868  time  servers
          available  to  the  client.   Servers  should  be listed in order of
          preference.

       option ien116-name-servers ip-address [, ip-address...  ];

          The ien116-name-servers option specifies a  list  of  IEN  116  name
          servers  available to the client.  Servers should be listed in order
          of preference.

       option domain-name-servers ip-address [, ip-address...  ];

          The domain-name-servers option  specifies  a  list  of  Domain  Name
          System  (STD  13,  RFC  1035)  name servers available to the client.
          Servers should be listed in order of preference.

       option log-servers ip-address [, ip-address...  ];

          The log-server option specifies a list of MIT-LCS  UDP  log  servers
          available  to  the  client.   Servers  should  be listed in order of
          preference.

       option cookie-servers ip-address [, ip-address...  ];

          The cookie server option specifies a list of RFC 865 cookie  servers
          available  to  the  client.   Servers  should  be listed in order of
          preference.

       option lpr-servers ip-address  [, ip-address...  ];

          The LPR server option specifies a list  of  RFC  1179  line  printer
          servers  available to the client.  Servers should be listed in order
          of preference.

       option impress-servers ip-address [, ip-address...  ];

          The impress-server option specifies a list of Imagen Impress servers
          available  to  the  client.   Servers  should  be listed in order of
          preference.

       option resource-location-servers ip-address [, ip-address...  ];

          This option specifies a list of RFC 887  Resource  Location  servers
          available  to  the  client.   Servers  should  be listed in order of
          preference.

       option host-name string;

          This option specifies the name of the client.  The name may  or  may
          not be qualified with the local domain name (it is preferable to use
          the domain-name option to specify the domain name).   See  RFC  1035
          for character set restrictions.

       option boot-size uint16;

          This  option specifies the length in 512-octet blocks of the default
          boot image for the client.

       option merit-dump string;

          This option specifies the path-name of a file to which the  client’s
          core  image  should  be dumped in the event the client crashes.  The
          path is formatted as a character  string  consisting  of  characters
          from the NVT ASCII character set.

       option domain-name string;

          This  option  specifies  the domain name that client should use when
          resolving hostnames via the Domain Name System.

       option swap-server ip-address;

          This specifies the IP address of the client’s swap server.

       option root-path string;

          This option specifies the path-name that contains the client’s  root
          disk.   The  path  is  formatted as a character string consisting of
          characters from the NVT ASCII character set.

       option ip-forwarding flag;

          This option specifies whether the client  should  configure  its  IP
          layer  for  packet  forwarding.   A  value  of  0  means  disable IP
          forwarding, and a value of 1 means enable IP forwarding.

       option non-local-source-routing flag;

          This option specifies whether the client  should  configure  its  IP
          layer  to allow forwarding of datagrams with non-local source routes
          (see Section 3.3.5 of [4] for a discussion of this topic).  A  value
          of  0  means disallow forwarding of such datagrams, and a value of 1
          means allow forwarding.

       option policy-filter ip-address ip-address [, ip-address  ip-address...
       ];

          This  option  specifies policy filters for non-local source routing.
          The filters consist of a  list  of  IP  addresses  and  masks  which
          specify  destination/mask pairs with which to filter incoming source
          routes.

          Any source routed datagram whose next-hop address does not match one
          of the filters should be discarded by the client.

          See STD 3 (RFC1122) for further information.

       option max-dgram-reassembly uint16;

          This  option  specifies  the  maximum  size datagram that the client
          should be prepared to reassemble.  The minimum value legal value  is
          576.

       option default-ip-ttl uint8;

          This  option  specifies  the  default  time-to-live  that the client
          should use on outgoing datagrams.

       option path-mtu-aging-timeout uint32;

          This option specifies the timeout (in seconds)  to  use  when  aging
          Path MTU values discovered by the mechanism defined in RFC 1191.

       option path-mtu-plateau-table uint16 [, uint16...  ];

          This  option  specifies  a table of MTU sizes to use when performing
          Path MTU Discovery as defined in RFC 1191.  The table  is  formatted
          as  a  list  of  16-bit  unsigned integers, ordered from smallest to
          largest.  The minimum MTU value cannot be smaller than 68.

       option interface-mtu uint16;

          This option specifies the  MTU  to  use  on  this  interface.    The
          minimum legal value for the MTU is 68.

       option all-subnets-local flag;

          This  option specifies whether or not the client may assume that all
          subnets of the IP network to which the client is connected  use  the
          same  MTU  as  the  subnet  of  that  network to which the client is
          directly connected.  A value of 1 indicates that all  subnets  share
          the same MTU.  A value of 0 means that the client should assume that
          some subnets of the directly  connected  network  may  have  smaller
          MTUs.

       option broadcast-address ip-address;

          This  option  specifies the broadcast address in use on the client’s
          subnet.  Legal values  for  broadcast  addresses  are  specified  in
          section 3.2.1.3 of STD 3 (RFC1122).

       option perform-mask-discovery flag;

          This  option  specifies  whether  or  not  the client should perform
          subnet mask discovery using ICMP.  A value of 0 indicates  that  the
          client  should  not perform mask discovery.  A value of 1 means that
          the client should perform mask discovery.

       option mask-supplier flag;

          This option specifies whether or not the client  should  respond  to
          subnet  mask  requests  using ICMP.  A value of 0 indicates that the
          client should not respond.  A value  of  1  means  that  the  client
          should respond.

       option router-discovery flag;

          This  option  specifies  whether  or  not  the client should solicit
          routers using the Router Discovery mechanism defined in RFC 1256.  A
          value  of  0  indicates  that  the  client should not perform router
          discovery.  A value of 1 means that the client should perform router
          discovery.

       option router-solicitation-address ip-address;

          This  option  specifies  the  address  to  which  the  client should
          transmit router solicitation requests.

       option static-routes ip-address ip-address [, ip-address  ip-address...
       ];

          This option specifies a list of static routes that the client should
          install in its routing  cache.   If  multiple  routes  to  the  same
          destination  are  specified,  they are listed in descending order of
          priority.

          The routes consist of a list of IP address pairs.  The first address
          is the destination address, and the second address is the router for
          the destination.

          The default route (0.0.0.0) is an illegal destination for  a  static
          route.  To specify the default route, use the routers option.

       option trailer-encapsulation flag;

          This option specifies whether or not the client should negotiate the
          use of trailers (RFC 893 [14]) when using the ARP protocol.  A value
          of  0  indicates that the client should not attempt to use trailers.
          A value of 1 means that the client should attempt to use trailers.

       option arp-cache-timeout uint32;

          This option specifies the timeout in seconds for ARP cache  entries.

       option ieee802-3-encapsulation flag;

          This  option specifies whether or not the client should use Ethernet
          Version 2 (RFC 894) or IEEE 802.3 (RFC 1042)  encapsulation  if  the
          interface  is  an  Ethernet.  A value of 0 indicates that the client
          should use RFC 894 encapsulation.  A  value  of  1  means  that  the
          client should use RFC 1042 encapsulation.

       option default-tcp-ttl uint8;

          This  option  specifies  the  default TTL that the client should use
          when sending TCP segments.  The minimum value is 1.

       option tcp-keepalive-interval uint32;

          This option specifies the interval (in seconds) that the client  TCP
          should  wait before sending a keepalive message on a TCP connection.
          The time is specified as a 32-bit unsigned integer.  A value of zero
          indicates  that the client should not generate keepalive messages on
          connections unless specifically requested by an application.

       option tcp-keepalive-garbage flag;

          This option specifies the whether or not the client should send  TCP
          keepalive  messages  with  a octet of garbage for compatibility with
          older implementations.  A value of 0 indicates that a garbage  octet
          should  not  be  sent.  A  value of 1 indicates that a garbage octet
          should be sent.

       option nis-domain string;

          This option specifies the name of  the  client’s  NIS  (Sun  Network
          Information   Services)  domain.   The  domain  is  formatted  as  a
          character  string  consisting  of  characters  from  the  NVT  ASCII
          character set.

       option nis-servers ip-address [, ip-address...  ];

          This  option specifies a list of IP addresses indicating NIS servers
          available to the client.  Servers  should  be  listed  in  order  of
          preference.

       option ntp-servers ip-address [, ip-address...  ];

          This  option  specifies  a  list of IP addresses indicating NTP (RFC
          1305) servers available to the client.  Servers should be listed  in
          order of preference.

       option netbios-name-servers ip-address [, ip-address...  ];

          The  NetBIOS  name  server  (NBNS)  option  specifies  a list of RFC
          1001/1002 NBNS name servers listed in order of preference.   NetBIOS
          Name  Service is currently more commonly referred to as WINS.   WINS
          servers can be specified using the netbios-name-servers option.

       option netbios-dd-server ip-address [, ip-address...  ];

          The NetBIOS datagram distribution server (NBDD) option  specifies  a
          list of RFC 1001/1002 NBDD servers listed in order of preference.

       option netbios-node-type uint8;

          The  NetBIOS  node  type  option  allows NetBIOS over TCP/IP clients
          which  are  configurable  to  be  configured  as  described  in  RFC
          1001/1002.    The  value  is  specified  as  a  single  octet  which
          identifies the client type.

          Possible node types are:

          1    B-node: Broadcast - no WINS

          2    P-node: Peer - WINS only.

          4    M-node: Mixed - broadcast, then WINS

          8    H-node: Hybrid - WINS, then broadcast

       option netbios-scope string;

          The NetBIOS scope option specifies the  NetBIOS  over  TCP/IP  scope
          parameter for the client as specified in RFC 1001/1002. See RFC1001,
          RFC1002, and RFC1035 for character-set restrictions.

       option font-servers ip-address [, ip-address...  ];

          This option specifies  a  list  of  X  Window  System  Font  servers
          available  to  the  client.  Servers  should  be  listed in order of
          preference.

       option x-display-manager ip-address [, ip-address...  ];

          This option specifies a list of  systems  that  are  running  the  X
          Window  System  Display  Manager  and  are  available to the client.
          Addresses should be listed in order of preference.

       option dhcp-client-identifier data-string;

          This option can be used to specify the a DHCP client identifier in a
          host declaration, so that dhcpd can find the host record by matching
          against the client identifier.
       option nisplus-domain string;

          This option specifies the name of the  client’s  NIS+  domain.   The
          domain  is  formatted as a character string consisting of characters
          from the NVT ASCII character set.
       option nisplus-servers ip-address [, ip-address...  ];

          This option specifies a list of IP addresses indicating NIS+ servers
          available  to  the  client.   Servers  should  be listed in order of
          preference.

       option tftp-server-name string;

          This option is used to identify a TFTP server and, if  supported  by
          the   client,  should  have  the  same  effect  as  the  server-name
          declaration.   BOOTP clients are unlikely to  support  this  option.
          Some DHCP clients will support it, and others actually require it.

       option bootfile-name string;

          This  option  is used to identify a bootstrap file.  If supported by
          the  client,  it  should  have  the  same  effect  as  the  filename
          declaration.   BOOTP  clients  are  unlikely to support this option.
          Some DHCP clients will support it, and others actually require it.

       option mobile-ip-home-agent ip-address [, ip-address... ];

          This option specifies a list of IP addresses  indicating  mobile  IP
          home  agents  available  to  the client.  Agents should be listed in
          order of preference, although normally there will be only  one  such
          agent.

       option smtp-server ip-address [, ip-address... ];

          The SMTP server option specifies a list of SMTP servers available to
          the client.  Servers should be listed in order of preference.

       option pop-server ip-address [, ip-address... ];

          The POP3 server option specifies a list of  POP3  available  to  the
          client.  Servers should be listed in order of preference.

       option nntp-server ip-address [, ip-address... ];

          The  NNTP  server  option  specifies a list of NNTP available to the
          client.  Servers should be listed in order of preference.

       option www-server ip-address [, ip-address... ];

          The WWW server option specifies a  list  of  WWW  available  to  the
          client.  Servers should be listed in order of preference.

       option finger-server ip-address [, ip-address... ];

          The Finger server option specifies a list of Finger available to the
          client.  Servers should be listed in order of preference.

       option irc-server ip-address [, ip-address... ];

          The IRC server option specifies a  list  of  IRC  available  to  the
          client.  Servers should be listed in order of preference.

       option streettalk-server ip-address [, ip-address... ];

          The  StreetTalk server option specifies a list of StreetTalk servers
          available to the client.  Servers  should  be  listed  in  order  of
          preference.

       option    streetalk-directory-assistance-server   ip-address   [,   ip-
       address... ];

          The StreetTalk Directory Assistance (STDA) server option specifies a
          list  of  STDA  servers  available to the client.  Servers should be
          listed in order of preference.

SEE ALSO

       dhcpd.conf(5),     dhcpd.leases(5),     dhclient.conf(5),     dhcpd(8),
       dhclient(8), RFC2132, RFC2131.

AUTHOR

       dhcpd(8)  was  written  by  Ted Lemon <mellon@vix.com> under a contract
       with Vixie Labs.    Funding  for  this  project  was  provided  by  the
       Internet Software Corporation.  Information about the Internet Software
       Consortium can be found at http://www.isc.org/isc.

                                                              dhcpd-options(5)