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If applicable, add the following below this CDDL HEADER, with the .\" fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner] .TH dhcpagent 1M "21 Sep 2009" "SunOS 5.11" "System Administration Commands" .SH NAME dhcpagent \- Dynamic Host Configuration Protocol (DHCP) client daemon .SH SYNOPSIS .LP .nf \fBdhcpagent\fR [\fB-a\fR] [ \fB-d\fR \fIn\fR] [\fB-f\fR] [\fB-v\fR] .fi .SH DESCRIPTION .sp .LP \fBdhcpagent\fR implements the client half of the Dynamic Host Configuration Protocol \fB(DHCP)\fR for machines running Solaris software. .sp .LP The \fBdhcpagent\fR daemon obtains configuration parameters for the client (local) machine's network interfaces from a \fBDHCP\fR server. These parameters may include a lease on an \fBIP\fR address, which gives the client machine use of the address for the period of the lease, which may be infinite. If the client wishes to use the \fBIP\fR address for a period longer than the lease, it must negotiate an extension using \fBDHCP\fR. For this reason, \fBdhcpagent\fR must run as a daemon, terminating only when the client machine powers down. .sp .LP For IPv4, the \fBdhcpagent\fR daemon is controlled through \fBifconfig\fR(1M) in much the same way that the \fBinit\fR(1M) daemon is controlled by \fBtelinit\fR(1M). \fBdhcpagent\fR can be invoked as a user process, albeit one requiring root privileges, but this is not necessary, as \fBifconfig\fR(1M) will start it automatically. .sp .LP For IPv6, the \fBdhcpagent\fR daemon is invoked automatically by \fBin.ndpd\fR(1M). It can also be controlled through \fBifconfig\fR(1M), if necessary. .sp .LP When invoked, \fBdhcpagent\fR enters a passive state while it awaits instructions from \fBifconfig\fR(1M) or \fBin.ndpd\fR(1M). When it receives a command to configure an interface, it brings up the interface (if necessary) and starts DHCP. Once DHCP is complete, \fBdhcpagent\fR can be queried for the values of the various network parameters. In addition, if DHCP was used to obtain a lease on an address for an interface, it configures the address for use. When a lease is obtained, it is automatically renewed as necessary. If the lease cannot be renewed, \fBdhcpagent\fR will unconfigure the address, but the interface will be left up and \fBdhcpagent\fR will attempt to acquire a new address lease. \fBdhcpagent\fR monitors system suspend/resume events and will validate any non-permanent leases with the DHCP server upon resume. Similarly, \fBdhcpagent\fR monitors link up/down events and will validate any non-permanent leases with the DHCP server when the downed link is brought back up. The lease validation mechanism will restart DHCP if the server indicates that the existing lease is no longer valid. If the server cannot be contacted, then the existing lease will continue. This behavior can be modified with the \fBVERIFIED_LEASE_ONLY\fR parameter in the \fB/etc/default/dhcpagent\fR file. See the description of this parameter below. .sp .LP For IPv4, if the configured interface is found to be unplumbed, or to have a different IP address, subnet mask, or broadcast address from those obtained from DHCP, the interface is abandoned from DHCP control. .sp .LP For IPv6, \fBdhcpagent\fR automatically plumbs and unplumbs logical interfaces as necessary for the IPv6 addresses supplied by the server. The IPv6 prefix length (netmask) is not set by the DHCPv6 protocol, but is instead set by \fBin.ndpd\fR(1M) using prefix information obtained by Router Advertisements. If any of the logical interfaces created by \fBdhcpagent\fR is unplumbed, or configured with a different IP address, it will be abandoned from DHCP control. If the link-local interface is unplumbed, then all addresses configured by DHCP on that physical interface will be removed. .sp .LP In addition to \fBDHCP\fR, \fBdhcpagent\fR also supports \fBBOOTP\fR (IPv4 only). See \fIRFC 951, Bootstrap Protocol\fR. Configuration parameters obtained from a \fBBOOTP\fR server are treated identically to those received from a \fBDHCP\fR server, except that the \fBIP\fR address received from a \fBBOOTP\fR server always has an infinite lease. .sp .LP \fBDHCP\fR also acts as a mechanism to configure other information needed by the client, for example, the domain name and addresses of routers. Aside from the IP address, and for IPv4 alone, the netmask, broadcast address, and default router, the agent does not directly configure the workstation, but instead acts as a database which may be interrogated by other programs, and in particular by \fBdhcpinfo\fR(1). .sp .LP On clients with a single interface, this is quite straightforward. Clients with multiple interfaces may present difficulties, as it is possible that some information arriving on different interfaces may need to be merged, or may be inconsistent. Furthermore, the configuration of the interfaces is asynchronous, so requests may arrive while some or all of the interfaces are still unconfigured. To handle these cases, one interface may be designated as primary, which makes it the authoritative source for the values of \fBDHCP\fR parameters in the case where no specific interface is requested. See \fBdhcpinfo\fR(1) and \fBifconfig\fR(1M) for details. .sp .LP For IPv4, the \fBdhcpagent\fR daemon can be configured to request a particular host name. See the \fBREQUEST_HOSTNAME\fR description in the \fBFILES\fR section. When first configuring a client to request a host name, you must perform the following steps as root to ensure that the full DHCP negotiation takes place: .sp .in +2 .nf # pkill dhcpagent # rm /etc/dhcp/\fIinterface\fR.dhc # reboot .fi .in -2 .sp .sp .LP All DHCP packets sent by \fBdhcpagent\fR include a vendor class identifier (RFC 2132, option code 60; RFC 3315, option code 16). This identifier is the same as the platform name returned by the \fBuname\fR \fB-i\fR command, except: .RS +4 .TP .ie t \(bu .el o Any commas in the platform name are changed to periods. .RE .RS +4 .TP .ie t \(bu .el o If the name does not start with a stock symbol and a comma, it is automatically prefixed with \fBSUNW\fR. .RE .SS "Messages" .sp .LP The \fBdhcpagent\fR daemon writes information and error messages in five categories: .sp .ne 2 .mk .na \fBcritical\fR .ad .sp .6 .RS 4n Critical messages indicate severe conditions that prevent proper operation. .RE .sp .ne 2 .mk .na \fBerrors\fR .ad .sp .6 .RS 4n Error messages are important, sometimes unrecoverable events due to resource exhaustion and other unexpected failure of system calls; ignoring errors may lead to degraded functionality. .RE .sp .ne 2 .mk .na \fBwarnings\fR .ad .sp .6 .RS 4n Warnings indicate less severe problems, and in most cases, describe unusual or incorrect datagrams received from servers, or requests for service that cannot be provided. .RE .sp .ne 2 .mk .na \fBinformational\fR .ad .sp .6 .RS 4n Informational messages provide key pieces of information that can be useful to debugging a \fBDHCP\fR configuration at a site. Informational messages are generally controlled by the \fB-v\fR option. However, certain critical pieces of information, such as the IP address obtained, are always provided. .RE .sp .ne 2 .mk .na \fBdebug\fR .ad .sp .6 .RS 4n Debugging messages, which may be generated at two different levels of verbosity, are chiefly of benefit to persons having access to source code, but may be useful as well in debugging difficult DHCP configuration problems. Debugging messages are only generated when using the \fB-d\fR option. .RE .sp .LP When \fBdhcpagent\fR is run without the \fB-f\fR option, all messages are sent to the system logger \fBsyslog\fR(3C) at the appropriate matching priority and with a facility identifier \fBLOG_DAEMON\fR. When \fBdhcpagent\fR is run with the \fB-f\fR option, all messages are directed to standard error. .SS "DHCP Events and User-Defined Actions" .sp .LP If an executable (binary or script) is placed at \fB/etc/dhcp/eventhook\fR, the \fBdhcpagent\fR deamon will automatically run that program when any of the following events occur: .sp .ne 2 .mk .na \fB\fBBOUND\fR and \fBBOUND6\fR\fR .ad .sp .6 .RS 4n These events occur during interface configuration. The event program is invoked when \fBdhcpagent\fR receives the DHCPv4 ACK or DHCPv6 Reply message from the DHCP server for the lease request of an address, indicating successful initial configuration of the interface. (See also the \fBINFORM\fR and \fBINFORM6\fR events, which occur when configuration parameters are obtained without address leases.) .RE .sp .ne 2 .mk .na \fB\fBEXTEND\fR and \fBEXTEND6\fR\fR .ad .sp .6 .RS 4n These events occur during lease extension. The event program is invoked just after \fBdhcpagent\fR receives the DHCPv4 ACK or DHCPv6 Reply from the DHCP server for the DHCPv4 REQUEST (renew) message or the DHCPv6 Renew or Rebind message. .sp Note that with DHCPv6, the server might choose to remove some addresses, add new address leases, and ignore (allow to expire) still other addresses in a given Reply message. The \fBEXTEND6\fR event occurs when a Reply is received that leaves one or more address leases still valid, even if the Reply message does not extend the lease for any address. The event program is invoked just before any addresses are removed, but just after any new addresses are added. Those to be removed will be marked with the \fBIFF_DEPRECATED\fR flag. .RE .sp .ne 2 .mk .na \fB\fBEXPIRE\fR and \fBEXPIRE6\fR\fR .ad .sp .6 .RS 4n These events occur during lease expiration. For DHCPv4, the event program is invoked just before the leased address is removed from an interface. For DHCPv6, the event program is invoked just before the last remaining leased addresses are removed from the interface. .RE .sp .ne 2 .mk .na \fB\fBDROP\fR and \fBDROP6\fR\fR .ad .sp .6 .RS 4n These events occur during the period when an interface is dropped. The event program is invoked just before the interface is removed from DHCP control. If the interface has been abandoned due the user unplumbing the interface, then this event will occur after the user's action has taken place. The interface might not be present. .RE .sp .ne 2 .mk .na \fB\fBINFORM\fR and \fBINFORM6\fR\fR .ad .sp .6 .RS 4n These events occur when an interface acquires new or updated configuration information from a DHCP server by means of the DHCPv4 \fBINFORM\fR or the DHCPv6 Information-Request message. These messages are sent using an \fBifconfig\fR(1M) \fBdhcp inform\fR command or when the DHCPv6 Router Advertisement \fBO\fR (letter 0) bit is set and the \fBM\fR bit is not set. Thus, these events occur when the DHCP client does not obtain an IP address lease from the server, and instead obtains only configuration parameters. .RE .sp .ne 2 .mk .na \fB\fBLOSS6\fR\fR .ad .sp .6 .RS 4n This event occurs during lease expiration when one or more valid leases still remain. The event program is invoked just before expired addresses are removed. Those being removed will be marked with the \fBIFF_DEPRECATED\fR flag. .sp Note that this event is not associated with the receipt of the Reply message, which occurs only when one or more valid leases remain, and occurs only with DHCPv6. If all leases have expired, then the EXPIRE6 event occurs instead. .RE .sp .ne 2 .mk .na \fB\fBRELEASE\fR and \fBRELEASE6\fR\fR .ad .sp .6 .RS 4n This event occurs during the period when a leased address is released. The event program is invoked just before \fBdhcpagent\fR relinquishes the address on an interface and sends the DHCPv4 \fBRELEASE\fR or DHCPv6 Release packet to the DHCP server. .RE .sp .LP The system does not provide a default event program. The file \fB/etc/dhcp/eventhook\fR is expected to be owned by root and have a mode of 755. .sp .LP The event program will be passed two arguments, the interface name and the event name, respectively. For DHCPv6, the interface name is the name of the physical interface. .sp .LP The event program can use the \fBdhcpinfo\fR(1) utility to fetch additional information about the interface. While the event program is invoked on every event defined above, it can ignore those events in which it is not interested. The event program runs with the same privileges and environment as \fBdhcpagent\fR itself, except that \fBstdin\fR, \fBstdout\fR, and \fBstderr\fR are redirected to \fB/dev/null\fR. Note that this means that the event program runs with root privileges. .sp .LP If an invocation of the event program does not exit after 55 seconds, it is sent a \fBSIGTERM\fR signal. If does not exit within the next three seconds, it is terminated by a \fBSIGKILL\fR signal. .sp .LP See EXAMPLES for an example event program. .SH OPTIONS .sp .LP The following options are supported: .sp .ne 2 .mk .na \fB\fB-a\fR\fR .ad .sp .6 .RS 4n Adopt a configured IPv4 interface. This option is for use with diskless \fBDHCP\fR clients. In the case of diskless \fBDHCP\fR, \fBDHCP\fR has already been performed on the network interface providing the operating system image prior to running \fBdhcpagent\fR. This option instructs the agent to take over control of the interface. It is intended primarily for use in boot scripts. .sp The effect of this option depends on whether the interface is being adopted. .sp If the interface is being adopted, the following conditions apply: .sp \fBdhcpagent\fR uses the client id specified in \fB/chosen\fR:\fI\fR, as published by the PROM or as specified on a \fBboot\fR(1M) command line. If this value is not present, the client id is undefined. The DHCP server then determines what to use as a client id. It is an error condition if the interface is an Infiniband interface and the PROM value is not present. .sp If the interface is not being adopted: .sp \fBdhcpagent\fR uses the value stored in \fB/etc/default/dhcpagent\fR. If this value is not present, the client id is undefined. If the interface is Infiniband and there is no value in \fB/etc/default/dhcpagent\fR, a client id is generated as described by the draft document on DHCP over Infiniband, available at: .sp .in +2 .nf http://www.ietf.org .fi .in -2 .RE .sp .ne 2 .mk .na \fB\fB-d\fR \fIn\fR\fR .ad .sp .6 .RS 4n Set debug level to \fIn\fR. Two levels of debugging are currently available, 1 and 2; the latter is more verbose. .RE .sp .ne 2 .mk .na \fB\fB-f\fR\fR .ad .sp .6 .RS 4n Run in the foreground instead of as a daemon process. When this option is used, messages are sent to standard error instead of to \fBsyslog\fR(3C). .RE .sp .ne 2 .mk .na \fB\fB-v\fR\fR .ad .sp .6 .RS 4n Provide verbose output useful for debugging site configuration problems. .RE .SH EXAMPLES .LP \fBExample 1 \fRExample Event Program .sp .LP The following script is stored in the file \fB/etc/dhcp/eventhook\fR, owned by root with a mode of 755. It is invoked upon the occurrence of the events listed in the file. .sp .in +2 .nf #!/bin/sh ( echo "Interface name: " $1 echo "Event: " $2 case $2 in "BOUND") echo "Address acquired from server "\e `/sbin/dhcpinfo -i $1 ServerID` ;; "BOUND6") echo "Addresses acquired from server " \e `/sbin/dhcpinfo -v6 -i $1 ServerID` ;; "EXTEND") echo "Lease extended for " \e `sbin/dhcpinfo -i $1 LeaseTim`" seconds" ;; "EXTEND6") echo "New lease information obtained on $i" ;; "EXPIRE" | "DROP" | "RELEASE") ;; esac ) >/var/run/dhcp_eventhook_output 2>&1 .fi .in -2 .sp .sp .LP Note the redirection of stdout and stderr to a file. .SH FILES .sp .ne 2 .mk .na \fB\fB/etc/dhcp/\fIif\fR.dhc\fR\fR .ad .br .na \fB\fB/etc/dhcp/\fIif\fR.dh6\fR\fR .ad .sp .6 .RS 4n Contains the configuration for interface. The mere existence of this file does not imply that the configuration is correct, since the lease might have expired. On start-up, \fBdhcpagent\fR confirms the validity of the address using REQUEST (for DHCPv4) or Confirm (DHCPv6). .RE .sp .ne 2 .mk .na \fB\fB/etc/dhcp/duid\fR\fR .ad .br .na \fB\fB/etc/dhcp/iaid\fR\fR .ad .sp .6 .RS 4n Contains persistent storage for DUID (DHCP Unique Identifier) and IAID (Identity Association Identifier) values. The format of these files is undocumented, and applications should not read from or write to them. .RE .sp .ne 2 .mk .na \fB\fB/etc/default/dhcpagent\fR\fR .ad .sp .6 .RS 4n Contains default values for tunable parameters. All values may be qualified with the interface they apply to by prepending the interface name and a period (".") to the interface parameter name. The parameters include: the interface parameter name. .sp To configure IPv6 parameters, place the string \fB\&.v6\fR between the interface name (if any) and the parameter name. For example, to set the global IPv6 parameter request list, use \fB\&.v6.PARAM_REQUEST_LIST\fR. To set the \fBCLIENT_ID\fR (\fBDUID\fR) on \fBhme0\fR, use \fBhme0.v6.CLIENT_ID\fR. .sp The parameters include: .sp .ne 2 .mk .na \fB\fBVERIFIED_LEASE_ONLY\fR\fR .ad .sp .6 .RS 4n Indicates that a \fBRELEASE\fR rather than a \fBDROP\fR should be performed on managed interfaces when the agent terminates. Release causes the client to discard the lease, and the server to make the address available again. Drop causes the client to record the lease in \fB/etc/dhcp/\fIinterface\fR.dhc\fR or \fB/etc/dhcp/\fIinterface\fR.dh6\fR for later use. In addition, when the link status changes to \fBup\fR or when the system is resumed after a suspend, the client will verify the lease with the server. If the server is unreachable for verification, then the old lease will be discarded (even if it has time remaining) and a new one obtained. .sp Enabling this option is often desirable on mobile systems, such as laptops, to allow the system to recover quickly from moves. .RE .sp .ne 2 .mk .na \fB\fBOFFER_WAIT\fR\fR .ad .sp .6 .RS 4n Indicates how long to wait between checking for valid \fBOFFER\fRs after sending a \fBDISCOVER\fR. For DHCPv6, sets the time to wait between checking for valid Advertisements after sending a Solicit. .RE .sp .ne 2 .mk .na \fB\fBCLIENT_ID\fR\fR .ad .sp .6 .RS 4n Indicates the value that should be used to uniquely identify the client to the server. This value can take one of three basic forms: .sp .in +2 .nf \fIdecimal\fR,\fIdata\fR... 0xHHHHH... "\fIstring\fR...." .fi .in -2 .sp The first form is an RFC 3315 DUID. This is legal for both IPv4 DHCP and DHCPv6. For IPv4, an RFC 4361 Client ID is constructed from this value. In this first form, the format of \fIdata\fR... depends on the decimal value. The following formats are defined for this first form: .sp .ne 2 .mk .na \fB1,\fIhwtype\fR,\fItime\fR,\fIlla\fR\fR .ad .sp .6 .RS 4n Type 1, DUID-LLT. The \fIhwtype\fR value is an integer in the range 0-65535, and indicates the type of hardware. The \fItime\fR value is the number of seconds since midnight, January 1st, 2000 UTC, and can be omitted to use the current system time. The \fIlla\fR value is either a colon-separated MAC address or the name of a physical interface. If the name of an interface is used, the \fIhwtype\fR value can be omitted. For example: \fB1,,,hme0\fR .RE .sp .ne 2 .mk .na \fB2,\fIenterprise\fR,\fIhex\fR...\fR .ad .sp .6 .RS 4n Type 2, DUID-EN. The \fIenterprise\fR value is an integer in the range 0-4294967295 and represents the SMI Enterprise number for an organization. The \fIhex\fR string is an even-length sequence of hexadecimal digits. .RE .sp .ne 2 .mk .na \fB3,\fIhwtype\fR,\fIlla\fR\fR .ad .sp .6 .RS 4n Type 3, DUID-LL. This is the same as DUID-LLT (type 1), except that a time stamp is not used. .RE .sp .ne 2 .mk .na \fB*,\fIhex\fR\fR .ad .sp .6 .RS 4n Any other type value (0 or 4-65535) can be used with an even-length hexadecimal string. .RE The second and third forms of \fBCLIENT_ID\fR are legal for IPv4 only. These both represent raw Client ID (without RFC 4361), in hex, or NVT ASCII string format. Thus, "\fBSun\fR" and \fB0x53756E\fR are equivalent. .RE .sp .ne 2 .mk .na \fB\fBPARAM_REQUEST_LIST\fR\fR .ad .sp .6 .RS 4n Specifies a list of comma-separated integer values of options for which the client would like values, or symbolic \fBSite\fR or \fBOption\fR option names. Symbolic option names for IPv4 are resolved through \fB/etc/dhcp/inittab\fR. Option names for IPv6 are resolved by means of \fB/etc/dhcp/inittab6\fR. .RE .sp .ne 2 .mk .na \fB\fBPARAM_IGNORE_LIST\fR\fR .ad .sp .6 .RS 4n Specifies a list of options (constructed in the same manner as \fBPARAM_REQUEST_LIST\fR) that the DHCP client will ignore. Ignored options are treated as though the server did not return the options specified. Ignored options are not visible using \fBdhcpinfo\fR(1) or acted on by the client. This parameter can be used, for example, to disable an unwanted client name or default router. .RE .sp .ne 2 .mk .na \fB\fBREQUEST_HOSTNAME\fR\fR .ad .sp .6 .RS 4n Indicates the client requests the DHCP server to map the client's leased IPv4 address to the host name associated with the network interface that performs DHCP on the client. The host name must be specified in the \fB/etc/hostname.\fIinterface\fR\fR file for the relevant interface on a line of the form .sp .in +2 .nf inet \fIhostname\fR .fi .in -2 .sp where \fIhostname\fR is the host name requested. .sp This option works with DHCPv4 only. .RE .RE .sp .ne 2 .mk .na \fB\fB/etc/dhcp/eventhook\fR\fR .ad .sp .6 .RS 4n Location of a DHCP event program. .RE .SH ATTRIBUTES .sp .LP See \fBattributes\fR(5) for descriptions of the following attributes: .sp .sp .TS tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) . ATTRIBUTE TYPEATTRIBUTE VALUE _ Interface StabilityCommitted .TE .SH SEE ALSO .sp .LP \fBdhcpinfo\fR(1), \fBifconfig\fR(1M), \fBinit\fR(1M), \fBin.mpathd\fR(1M), \fBin.ndpd\fR(1M), \fBsyslog\fR(3C), \fBattributes\fR(5), \fBdhcp\fR(5) .sp .LP \fI\fR .sp .LP Croft, B. and Gilmore, J.,\fIBootstrap Protocol (BOOTP)\fRRFC 951, Network Working Group, September 1985. .sp .LP Droms, R., \fIDynamic Host Configuration Protocol\fR, RFC 2131, Network Working Group, March 1997. .sp .LP Lemon, T. and B. Sommerfeld. \fIRFC 4361, Node-specific Client Identifiers for Dynamic Host Configuration Protocol Version Four (DHCPv4)\fR. Nominum and Sun Microsystems. February 2006. .sp .LP Droms, R. \fIRFC 3315, Dynamic Host Configuration Protocol for IPv6 (DHCPv6)\fR. Cisco Systems. July 2003. .SH NOTES .sp .LP The \fBdhcpagent\fR daemon can be used on IPv4 logical interfaces, just as with physical interfaces. When used on a logical interface, the daemon automatically constructs a Client ID value based on the DUID and IAID values, according to RFC 4361. The \fB/etc/default/dhcpagent\fR \fBCLIENT_ID\fR value, if any, overrides this automatic identifier. .sp .LP As with physical IPv4 interfaces, the \fB/etc/hostname.hme0:1\fR and \fB/etc/dhcp.hme0:1\fR files must also be created in order for \fBhme0:1\fR to be automatically plumbed and configured at boot. In addition, unlike physical IPv4 interfaces, \fBdhcpagent\fR does not add or remove default routes associated with logical interfaces. .sp .LP DHCP can be performed on IPMP IP interfaces to acquire and maintain IPMP data addresses. Because an IPMP IP interface has no hardware address, the daemon automatically constructs a Client ID using the same approach described above for IPv4 logical interfaces. In addition, the lack of a hardware address means the daemon must set the "broadcast" flag in all \fBDISCOVER\fR and \fBREQUEST\fR messages on IPMP IP interfaces. Some DHCP servers may refuse such requests. .sp .LP DHCP can be performed on IP interfaces that are part of an IPMP group (to acquire and maintain test addresses). The daemon will automatically set the \fBNOFAILOVER\fR and \fBDEPRECATED\fR flags on each test address. Additionally, the daemon will not add or remove default routes in this case. Note that the actual DHCP packet exchange may be performed over any active IP interface in the IPMP group. It is strongly recommended that test addresses have infinite leases. Otherwise, an extended network outage detectable only by probes may cause test address leases to expire, causing \fBin.mpathd\fR(1M) to revert to link-based failure detection and trigger an erroneous repair. .sp .LP With DHCPv6, the link-local interface must be configured using \fB/etc/hostname6.hme0\fR in order for DHCPv6 to run on \fBhme0\fR at boot time. The logical interfaces for each address are plumbed by \fBdhcpagent\fR automatically.