DHCP6C(8) System Manager's Manual DHCP6C(8)

dhcp6c — DHCPv6 client daemon

dhcp6c [-c configfile] [-Ddfi] [-p pid-file] [-P profile] interface [interfaces...]

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:

configfile
Use configfile as the configuration file.
Print debugging messages.
Even more debugging information is printed.
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.
Info-req mode. In this mode, stateless DHCPv6 is executed with the following 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.

pid-file
Use pid-file to dump the process ID of dhcp6c.
profile
Use the given profile defined in the dhcp6c configuration file for interfaces which do not have a specific configuration.

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

Upon receipt of the SIGHUP or SIGTERM signals, dhcp6c will remove all stateful resources from the system. In the former case the daemon will then reinvoke itself, while it will stop running in the latter case. In either case, dhcp6c will send DHCPv6 Release messages to release resources assigned from servers.

/var/run/dhcp6c.pid
is the default file that contains pid of the currently running dhcp6c.
/etc/wide-dhcpv6/dhcp6c.conf
is the default configuration file.
/var/lib/dhcpv6/dhcp6c_duid
is the file to store the client's DUID.

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:

The reason why the script is invoked. As of this writing, the value is always "NBI" and thus meaningless.
A list of available DNS servers, each of which is an IPv6 numeric address and is separated by a white space character.
A list of DNS names, which provides DNS name search path.
A list of available NTP servers, each of which is an IPv6 numeric address and is separated by a white space character.
A list of available SIP server addresses, each of which is an IPv6 numeric address and is separated by a white space character.
A list of SIP server domain names.
A list of available NIS server addresses, each of which is an IPv6 numeric address and is separated by a white space character.
A list of NIS domain names.
A list of available NIS+ server addresses, each of which is an IPv6 numeric address and is separated by a white space character.
A list of NIS+ domain names.
A list of available BCMCS server addresses, each of which is an IPv6 numeric address and is separated by a white space character.
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.

daemon(3), dhcp6c.conf(5), dhcp6s(8)

Ralph Droms, Editor, Dynamic Host Configuration Protocol for IPv6 (DHCPv6), RFC 3315, 2003.

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

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 recognized in Info-req mode, since dhcp6c terminates after it receives a REPLY message.

September 12, 1999 KAME