NAME
dhcp6c.conf - DHCPv6 client configuration file
SYNOPSIS
/etc/wide-dhcpv6/dhcp6c.conf
DESCRIPTION
The dhcp6c.conf file contains configuration information for KAME’s DHCPv6
client, dhcp6c. The configuration file consists of a sequence of
statements terminated by a semi-colon (‘;’). Statements are composed of
tokens separated by white space, which can be any combination of blanks,
tabs and newlines. In some cases a set of statements is combined with a
pair of brackets, which is regarded as a single token. Lines beginning
with ‘#’ are comments.
Interface specification
There are some statements that may or have to specify interface.
Interfaces are specified in the form of "name unit", such as fxp0 and
gif1.
DHCPv6 options
Some configuration statements take the description of a DHCPv6 option as
an argument. The followings are the format and description of available
DHCPv6 options.
domain-name-servers
means a Domain Name Server option.
domain-name
means a domain name option.
ntp-servers
means an NTP server option. As of this writing, the option type
for this option is not officially assigned. dhcp6c will reject
this option unless it is explicitly built to accept the option.
sip-server-address
means a SIP Server address option.
sip-server-domain-name
means a SIP server domain name option.
nis-server-address
means a NIS Server address option.
nis-domain-name
means a NIS domain name option.
nisp-server-address
means a NIS+ Server address option.
nisp-domain-name
means a NIS+ domain name option.
bcmcs-server-address
means a BCMCS Server address option.
bcmcs-server-domain-name
means a BCMCS server domain name option.
ia-pd ID
means an IA_PD (Identity Association for Prefix Delegation)
option. ID is a decimal number of the IAID (see below about
identity associations).
ia-na ID
means an IA_PD (Identity Association for Non-temporary Addresses)
option. ID is a decimal number of the IAID (see below about
identity associations).
rapid-commit
means a rapid-commit option.
authentication authname
means an authentication option. authname is a string specifying
parameters of the authentication protocol. An authentication
statement for authname must be provided.
Interface statement
An interface statement specifies configuration parameters on the
interface. The generic format of an interface statement is as follows:
interface interface { substatements };
The followings are possible substatements in an interface
statement.
send send-options ;
This statement specifies DHCPv6 options to be sent to the
server(s). Some options can only appear in particular
messages according to the specification, in which case
the appearance of the options is limited to be compliant
with the specification.
send-options is a comma-separated list of options, each
of which should be specified as described above.
Multiple send statements can also be specified, in which
case all the specified options will be sent.
When rapid-commit is specified, dhcp6c will include a
rapid-commit option in solicit messages and wait for an
immediate reply instead of advertisements.
When ia-pd is specified, dhcp6c will initiate prefix
delegation as a requesting router by including an IA_PD
option with the specified ID in solicit messages.
When ia-na is specified, dhcp6c will initiate stateful
address assignment by including an IA_NA option with the
specified ID in solicit messages.
In either case, a corresponding identity association
statement must exist with the same ID.
request request-options;
This statement specifies DHCPv6 options to be included in
an option-request option. request-options is a comma-
separated list of options, which can consist of the
following options.
domain-name-servers
requests a list of Domain Name Server addresses.
domain-name
requests a DNS search path.
ntp-servers
requests a list of NTP server addresses. As of
this writing, the option type for this option is
not officially assigned. dhcp6c will reject this
option unless it is explicitly built to accept
the option.
sip-server-address
requests a list of SIP server addresses.
sip-domain-name
requests a SIP server domain name.
nis-server-address
requests a list of NIS server addresses.
nis-domain-name
requests a NIS domain name.
nisp-server-address
requests a list of NIS+ server addresses.
nisp-domain-name
requests a NIS+ domain name.
bcmcs-server-address
requests a list of BCMCS server addresses.
bcmcs-domain-name
requests a BCMCS domain name.
refreshtime
means an information refresh time option. This
can only be specified when sent with information-
request messages; dhcp6c will ignore this option
for other messages.
Multiple request statements can also be specified, in
which case all the specified options will be requested.
information-only;
This statement specifies dhcp6c to only exchange
informational configuration parameters with servers. A
list of DNS server addresses is an example of such
parameters. This statement is useful when the client
does not need stateful configuration parameters such as
IPv6 addresses or prefixes.
script "script-name";
This statement specifies a path to script invoked by
dhcp6c on a certain condition including when the daemon
receives a reply message. script-name must be the
absolute path from root to the script file, be a regular
file, and be created by the same owner who runs the
daemon.
Profile statement
Some setups may require to configure an interface independently from its
name. Profiles are available for this particular purpose. They follow
the same syntax as an interface statement except they can be arbitrarily
named. It is then possible to choose which profile to use for a given
interface on the command line.
Identity association statement
Identity association (IA) is a key notion of DHCPv6. An IA is uniquely
identified in a client by a pair of IA type and IA identifier (IAID). An
IA is associated with configuration information dependent on the IA type.
An identity association statement defines a single IA with some client-
side configuration parameters. Its format is as follows:
id-assoc type [ID] { substatements };
type is a string for the type of this IA. The current
implementation supports ‘na’ (non-temporary address allocation)
‘pd’ (prefix delegation) for the IA type. ID is a decimal number
of IAID. If omitted, the value 0 will be used by default.
substatements is a sequence of statements that specifies
configuration parameters for this IA. Each statement may or may
not be specific to the type of IA.
The followings are possible substatements for an IA of type na.
address ipv6-address pltime [vltime];
specifies an address and related parameters that the
client wants to be allocated. Multiple addresses can be
specified, each of which is described as a separate
address substatement. dhcp6c will include all the
addresses (and related parameters) in Solicit messages,
as an IA_NA prefix option encapsulated in the
corresponding IA_NA option. Note, however, that the
server may or may not respect the specified prefix
parameters. For parameters of the address substatement,
see dhcp6s.conf(5).
The followings are possible substatements for an IA of type pd.
prefix_interface_statement
specifies the client’s local configuration of how
delegated prefixes should be used (see below).
prefix ipv6-prefix pltime [vltime];
specifies a prefix and related parameters that the client
wants to be delegated. Multiple prefixes can be
specified, each of which is described as a separate
prefix substatement. dhcp6c will include all the
prefixes (and related parameters) in Solicit messages, as
an IA_PD prefix option encapsulated in the corresponding
IA_PD option. Note, however, that the server may or may
not respect the specified prefix parameters. For
parameters of the prefix substatement, see
dhcp6s.conf(5).
Prefix interface statement
A prefix interface statement specifies configuration parameters of
prefixes on local interfaces that are derived from delegated prefixes. A
prefix interface statement can only appear as a substatement of an
identity association statement with the type pd. The generic format of
an interface statement is as follows:
prefix-interface interface { substatements };
When an IPv6 prefix is delegated from a DHCPv6 server, dhcp6c
will assign a prefix on the interface unless the interface
receives the DHCPv6 message that contains the prefix with the
delegated prefix and the parameters provided in substatements.
Possible substatements are as follows:
sla-id ID ;
This statement specifies the identifier value of the
site-level aggregator (SLA) on the interface. ID must be
a decimal integer which fits in the length of SLA IDs
(see below). For example, if ID is 1 and the client is
delegated an IPv6 prefix 2001:db8:ffff::/48, dhcp6c will
combine the two values into a single IPv6 prefix,
2001:db8:ffff:1::/64, and will configure the prefix on
the specified interface.
sla-len length ;
This statement specifies the length of the SLA ID in
bits. length must be a decimal number between 0 and 128.
If the length is not specified by this statement, the
default value 16 will be used.
Authentication statement
An authentication statement defines a set of authentication parameters
used in DHCPv6 exchanges with the server(s). The format of an
authentication statement is as follows:
authentication authname { substatements };
authname is a string which is unique among all authentication
statements in the configuration file. It will specify a
particular set of authentication parameters when authentication
option is specified in the interface statement. Possible
substatements of the authentication statement are as follows:
protocol authprotocol ;
specifies the authentication protocol. Currently, the
only available protocol as authprotocol is delayed, which
means the DHCPv6 delayed authentication protocol.
algorithm authalgorithm ;
specifies the algorithm for this authentication.
Currently, the only available algorithm is HMAC-MD5,
which can be specified as one of the followings:
hmac-md5, HMAC-MD5, hmacmd5, or HMACMD5. This
substatement can be omitted. In this case, HMAC-MD5 will
be used as the algorithm.
rdm replay-detection-method ;
specifies the replay protection method for this
authentication. Currently, the only available method is
monocounter, which means the use of a monotonically
increasing counter. If this method is specified, dhcp6c
will use an NTP-format timestamp when it authenticates
the message. This substatement can be omitted, in which
case monocounter will be used as the method.
Keyinfo statement
A keyinfo statement defines a secret key shared with the server(s) to
authenticate DHCPv6 messages. The format of a keyinfo statement is as
follows:
keyinfo keyname { substatements };
keyname is an arbitrary string. It does not affect client’s
behavior but is provided for readability of log messages.
Possible substatements of the keyinfo statement are as follows:
realm "realmname" ;
specifies the DHCP realm. realmname is an arbitrary
string, but is typically expected to be a domain name
like "kame.net" .
keyid ID ;
specifies the key identifier, ID, as a decimal number. A
secret key is uniquely identified within the client by
the DHCP realm and the key identifier.
secret "secret-value" ;
specifies the shared secret of this key. "secret-value"
is a base-64 encoded string of the secret.
expire "expiration-time" ;
specifies the expiration time of this key.
"expiration-time" should be formatted in one of the
followings: yyyy-mm-dd HH:MM, mm-dd HH:MM, or HH:MM,
where yyyy is the year with century (e.g., 2004), mm is
the month, dd is the day of the month, HH is the hour of
24-hour clock, and MM is the minute, each of which is
given as a decimal number. Additionally, a special
keyword forever can be specified as expiration-time,
which means the key has an infinite lifetime and never
expires. This substatement can be omitted, in which case
forever will be used by default.
Examples
The followings are a sample configuration to be delegated an IPv6 prefix
from an upstream service provider. With this configuration dhcp6c will
send solicit messages containing an IA_PD option, with an IAID 0, on to
an upstream PPP link, ppp0. After receiving some prefixes from a server,
dhcp6c will then configure derived IPv6 prefixes with the SLA ID 1 on a
local ethernet interface, ne0. Note that the IAID for the id-assoc
statement is 0 according to the default.
interface ppp0 {
send ia-pd 0;
};
id-assoc pd {
prefix-interface ne0 {
sla-id 1;
};
};
If a shared secret should be configured in both the client and the server
for DHCPv6 authentication, it would be specified in the configuration
file as follows:
keyinfo kame-key {
realm "kame.net";
keyid 1;
secret "5pvW2g48OHPvkYMJSw0vZA==";
};
One easy way of generating a new secret in the base64 format is to
execute the openssl(1) command (when available) as follows,
% openssl rand -base64 16
and copy the output to the dhcp6c.conf file.
To include an authentication option for DHCPv6 authentication, the
interface statement should be modified and an authentication statement
should be added as follows:
interface ppp0 {
send ia-pd 0;
send authentication kame;
};
authentication kame {
protocol delayed;
};
interface fxp0 {
send ia-na 0;
};
SEE ALSO
dhcp6s.conf(5) dhcp6c(8)
HISTORY
The dhcp6c.conf configuration file first appeared in the WIDE/KAME IPv6
protocol stack kit.