NAME

dhcp6c — DHCPv6 client daemon

SYNOPSIS

dhcp6c [-c configfile] [-Ddfin] [-p pid-file] interface [interfaces...]

DESCRIPTION

dhcp6c works as a DHCPv6 client and gets information from DHCPv6 servers to configure the specified interface. Multiple interfaces can be specified separated by spaces or tabs, in which case dhcp6c will work on all the interfaces simultaneously.

The command line options are:

-c configfile

Use configfile as the configuration file.

-d

Print debugging messages.

-D

Even more debugging information is printed.

-f

Foreground mode (useful when debugging). Although dhcp6c usually prints warning, debugging, or error messages to syslog(8), it prints the messages to standard error if this option is specified.

-i

Info-req mode. In this mode, stateless DHCPv6 is executed with the folllowing configuration, and the obtained info is written to stdout. After this output, dhcp6c is terminated. (suits for a use in shell-script etc).

 interface (interface given in the argument) {
	information-only;
	script (a script which displays the received information to stdout);
 };

Since the configuration is internally generated, you cannot provide a configuration in this mode. If you want to have different actions for the stateless DHCPv6 information, you should write an appropriate configuration and invoke dhcp6c without this option.

-n

Prevent Release message from being sent to DHCPv6 server when dhcp6c stops. This is useful for preventing a new address from being configured by the DHCPv6 server when restarting the DHCPv6 client.

-p pid-file

Use pid-file to dump the process ID of dhcp6c.

The program will daemonize itself on invocation unless the -f or -i option is specified.

Upon receipt of a SIGHUP, SIGTERM, or SIGUSR1 signal, dhcp6c will remove all stateful resources from the system. After that, SIGHUP reinitializes the daemon, and SIGTERM stops the daemon. In both cases, DHCPv6 Release message will be sent to release resources assigned from servers. SIGUSR1 stops the daemon as SIGTERM does though DHCPv6 Release message will not be sent.

FILES

/var/run/dhcp6c.pid: is the default file that contains pid of the currently running dhcp6c.
/usr/local/etc/dhcp6c.conf: is the default configuration file.
/var/db/dhcp6c_duid: is the file to store the client's DUID.

Configuration Script

When dhcp6c receives a reply message, it will invoke a supplementary configuration script specified in the dhcp6c.conf(5) file. The daemon will provide the script with configuration parameters as environment variables, which include:

REASON

The reason why the script is invoked. One of the following values is set based on a message which the client sent before the REPLY message arrives:

INFOREQ: The client sent an INFORMATION REQUEST message.
REQUEST: The client sent a REQUEST message.
RENEW: The client sent a RENEW message.
REBIND: The client sent a REBIND message.
RELEASE: The client sent a RELEASE message.
EXIT: This happens when dhcp6c exits.

new_domain_name_servers

A list of available DNS servers, each of which is an IPv6 numeric address and is separated by a white space character.

new_domain_name

A list of DNS names, which provides DNS name search path.

new_ntp_servers

A list of available NTP servers, each of which is an IPv6 numeric address and is separated by a white space character.

new_sip_servers

A list of available SIP server addresses, each of which is an IPv6 numeric address and is separated by a white space character.

new_sip_name

A list of SIP server domain names.

new_nis_servers

A list of available NIS server addresses, each of which is an IPv6 numeric address and is separated by a white space character.

new_nis_name

A list of NIS domain names.

new_nisp_servers

A list of available NIS+ server addresses, each of which is an IPv6 numeric address and is separated by a white space character.

new_nisp_name

A list of NIS+ domain names.

new_bcmcs_servers

A list of available BCMCS server addresses, each of which is an IPv6 numeric address and is separated by a white space character.

new_bcmcs_name

A list of BCMCS server domain names.

Note that the daemon does not always provide all the parameters. It sets an environment variable only when the corresponding configuration parameter is provided by the DHCPv6 server.

HISTORY

The dhcp6c command first appeared in WIDE/KAME IPv6 protocol stack kit.

BUGS

dhcp6c is incomplete and violates DHCPv6 protocol spec, in several aspects. In particular, temporary address assignment is intentionally omitted.

Information Refresh Time Option is not recognied in Info-req mode, since dhcp6c terminates after it receives a REPLY message.