--- embedaddon/dhcp/client/dhclient.conf.5 2012/02/21 22:30:18 1.1 +++ embedaddon/dhcp/client/dhclient.conf.5 2012/10/09 09:06:54 1.1.1.1 @@ -1,6 +1,6 @@ -.\" $Id: dhclient.conf.5,v 1.1 2012/02/21 22:30:18 misho Exp $ +.\" $Id: dhclient.conf.5,v 1.1.1.1 2012/10/09 09:06:54 misho Exp $ .\" -.\" Copyright (c) 2009-2011 by Internet Systems Consortium, Inc. ("ISC") +.\" Copyright (c) 2009-2012 by Internet Systems Consortium, Inc. ("ISC") .\" Copyright (c) 2004,2007 by Internet Systems Consortium, Inc. ("ISC") .\" Copyright (c) 1996-2003 by Internet Software Consortium .\" @@ -36,11 +36,11 @@ The dhclient.conf file contains configuration informat .IR dhclient, the Internet Systems Consortium DHCP Client. .PP -The dhclient.conf file is a free-form ASCII text file. It is parsed by -the recursive-descent parser built into dhclient. The file may contain +The dhclient.conf file is a free-form ASCII text file. It is parsed by +the recursive-descent parser built into dhclient. The file may contain extra tabs and newlines for formatting purposes. Keywords in the file -are case-insensitive. Comments may be placed anywhere within the -file (except within quotes). Comments begin with the # character and +are case-insensitive. Comments may be placed anywhere within the +file (except within quotes). Comments begin with the # character and end at the end of the line. .PP The dhclient.conf file can be used to configure the behaviour of the @@ -74,12 +74,12 @@ The statement determines the amount of time that must pass between the time that the client begins to try to determine its address and the time that it decides that it's not going to be able to contact a -server. By default, this timeout is sixty seconds. After the +server. By default, this timeout is sixty seconds. After the timeout has passed, if there are any static leases defined in the configuration file, or any leases remaining in the lease database that have not yet expired, the client will loop through these leases attempting to validate them, and if it finds one that appears to be -valid, it will use that lease's address. If there are no valid +valid, it will use that lease's address. If there are no valid static leases or unexpired leases in the lease database, the client will restart the protocol after the defined retry interval. .PP @@ -93,7 +93,7 @@ The .I retry statement determines the time that must pass after the client has determined that there is no DHCP server present before it tries again -to contact a DHCP server. By default, this is five minutes. +to contact a DHCP server. By default, this is five minutes. .PP .I The .B select-timeout @@ -102,9 +102,9 @@ to contact a DHCP server. By default, this is five m \fBselect-timeout \fItime\fR\fB;\fR .PP It is possible (some might say desirable) for there to be more than -one DHCP server serving any given network. In this case, it is +one DHCP server serving any given network. In this case, it is possible that a client may be sent more than one offer in response to -its initial lease discovery message. It may be that one of these +its initial lease discovery message. It may be that one of these offers is preferable to the other (e.g., one offer may have the address the client previously used, and the other may not). .PP @@ -112,7 +112,7 @@ The .I select-timeout is the time after the client sends its first lease discovery request at which it stops waiting for offers from servers, assuming that it -has received at least one such offer. If no offers have been +has received at least one such offer. If no offers have been received by the time the .I select-timeout has expired, the client will accept the first offer that arrives. @@ -127,13 +127,13 @@ will take the first offer it sees. \fBreboot \fItime\fR\fB;\fR .PP When the client is restarted, it first tries to reacquire the last -address it had. This is called the INIT-REBOOT state. If it is +address it had. This is called the INIT-REBOOT state. If it is still attached to the same network it was attached to when it last -ran, this is the quickest way to get started. The +ran, this is the quickest way to get started. The .I reboot statement sets the time that must elapse after the client first tries to reacquire its old address before it gives up and tries to discover -a new address. By default, the reboot timeout is ten seconds. +a new address. By default, the reboot timeout is ten seconds. .PP .I The .B backoff-cutoff @@ -143,11 +143,12 @@ a new address. By default, the reboot timeout is ten .PP The client uses an exponential backoff algorithm with some randomness, so that if many clients try to configure themselves at the same time, -they will not make their requests in lockstep. The +they will not make their requests in lockstep. The .I backoff-cutoff statement determines the maximum amount of time that the client is allowed to back off, the actual value will be evaluated randomly between -1/2 to 1 1/2 times the \fItime\fR specified. It defaults to two minutes. +1/2 to 1 1/2 times the \fItime\fR specified. It defaults to fifteen +seconds. .PP .I The .B initial-interval @@ -181,7 +182,7 @@ to 5. .SH LEASE REQUIREMENTS AND REQUESTS The DHCP protocol allows the client to request that the server send it specific information, and not send it other information that it is not -prepared to accept. The protocol also allows the client to reject +prepared to accept. The protocol also allows the client to reject offers from servers if they don't contain information the client needs, or if the information provided is not satisfactory. .PP @@ -198,8 +199,8 @@ are called \fIDHCP Options\fR. DHCP Options are defin .PP The request statement causes the client to request that any server responding to the client send the client its values for the specified -options. Only the option names should be specified in the request -statement - not option parameters. By default, the DHCPv4 client +options. Only the option names should be specified in the request +statement - not option parameters. By default, the DHCPv4 client requests the subnet-mask, broadcast-address, time-offset, routers, domain-name, domain-name-servers and host-name options while the DHCPv6 client requests the dhcp6 name-servers and domain-search options. Note @@ -207,7 +208,7 @@ that if you enter a \'request\' statement, you over-ri and these options will not be requested. .PP In some cases, it may be desirable to send no parameter request list -at all. To do this, simply write the request statement but specify +at all. To do this, simply write the request statement but specify no parameters: .PP .nf @@ -229,7 +230,7 @@ is best to \'also request\' the additional options: \fB[ also ] require [ [ \fIoption-space\fR . ] \fIoption\fR ] [\fB,\fI ... ]\fB;\fR .PP The require statement lists options that must be sent in order for an -offer to be accepted. Offers that do not contain all the listed +offer to be accepted. Offers that do not contain all the listed options will be ignored. There is no default require list. .PP .nf @@ -257,15 +258,15 @@ that will allow it to differentiate between this clien clients or kinds of clients. .SH DYNAMIC DNS The client now has some very limited support for doing DNS updates -when a lease is acquired. This is prototypical, and probably doesn't -do what you want. It also only works if you happen to have control +when a lease is acquired. This is prototypical, and probably doesn't +do what you want. It also only works if you happen to have control over your DNS server, which isn't very likely. .PP Note that everything in this section is true whether you are using DHCPv4 or DHCPv6. The exact same syntax is used for both. .PP To make it work, you have to declare a key and zone as in the DHCP -server (see \fBdhcpd.conf\fR(5) for details). You also need to +server (see \fBdhcpd.conf\fR(5) for details). You also need to configure the fqdn option on the client, as follows: .PP .nf @@ -276,8 +277,8 @@ configure the fqdn option on the client, as follows: .fi .PP The \fIfqdn.fqdn\fR option \fBMUST\fR be a fully-qualified domain -name. You \fBMUST\fR define a zone statement for the zone to be -updated. The \fIfqdn.encoded\fR option may need to be set to +name. You \fBMUST\fR define a zone statement for the zone to be +updated. The \fIfqdn.encoded\fR option may need to be set to \fIon\fR or \fIoff\fR, depending on the DHCP server you are using. .PP .I The @@ -291,16 +292,16 @@ script (see \fBdhclient-script(8)\fR) rather than havi DHCP client do the update directly (for example, if you want to use SIG(0) authentication, which is not supported directly by the DHCP client, you can instruct the client not to do the update using -the \fBdo-forward-updates\fR statement. \fIFlag\fR should be \fBtrue\fR +the \fBdo-forward-updates\fR statement. \fIFlag\fR should be \fBtrue\fR if you want the DHCP client to do the update, and \fBfalse\fR if -you don't want the DHCP client to do the update. By default, the DHCP +you don't want the DHCP client to do the update. By default, the DHCP client will do the DNS update. .SH OPTION MODIFIERS In some cases, a client may receive option data from the server which is not really appropriate for that client, or may not receive information that it needs, and for which a useful default value -exists. It may also receive information which is useful, but which -needs to be supplemented with local information. To handle these +exists. It may also receive information which is useful, but which +needs to be supplemented with local information. To handle these needs, several option modifiers are available. .PP .I The @@ -337,10 +338,10 @@ If for some set of options the client should use a val supply, and then use the values supplied by the server, if any, these values can be defined in the .B prepend -statement. The +statement. The .B prepend statement can only be used for options which -allow more than one value to be given. This restriction is not +allow more than one value to be given. This restriction is not enforced - if you ignore it, the behaviour will be unpredictable. .PP .I The @@ -353,10 +354,10 @@ If for some set of options the client should first use supplied by the server, if any, and then use values you supply, these values can be defined in the .B append -statement. The +statement. The .B append statement can only be used for options which -allow more than one value to be given. This restriction is not +allow more than one value to be given. This restriction is not enforced - if you ignore it, the behaviour will be unpredictable. .SH LEASE DECLARATIONS .PP @@ -368,12 +369,12 @@ enforced - if you ignore it, the behaviour will be unp .PP The DHCP client may decide after some period of time (see \fBPROTOCOL TIMING\fR) that it is not going to succeed in contacting a -server. At that time, it consults its own database of old leases and +server. At that time, it consults its own database of old leases and tests each one that has not yet timed out by pinging the listed router -for that lease to see if that lease could work. It is possible to +for that lease to see if that lease could work. It is possible to define one or more \fIfixed\fR leases in the client configuration file for networks where there is no DHCP or BOOTP service, so that the -client can still automatically configure its address. This is done +client can still automatically configure its address. This is done with the .B lease statement. @@ -381,12 +382,12 @@ statement. NOTE: the lease statement is also used in the dhclient.leases file in order to record leases that have been received from DHCP servers. Some of the syntax for leases as described below is only needed in the -dhclient.leases file. Such syntax is documented here for +dhclient.leases file. Such syntax is documented here for completeness. .PP A lease statement consists of the lease keyword, followed by a left curly brace, followed by one or more lease declaration statements, -followed by a right curly brace. The following lease declarations +followed by a right curly brace. The following lease declarations are possible: .PP \fBbootp;\fR @@ -394,8 +395,8 @@ are possible: The .B bootp statement is used to indicate that the lease was acquired using the -BOOTP protocol rather than the DHCP protocol. It is never necessary -to specify this in the client configuration file. The client uses +BOOTP protocol rather than the DHCP protocol. It is never necessary +to specify this in the client configuration file. The client uses this syntax in its lease database file. .PP \fBinterface\fR \fB"\fR\fIstring\fR\fB";\fR @@ -403,8 +404,8 @@ this syntax in its lease database file. The .B interface lease statement is used to indicate the interface on which the lease -is valid. If set, this lease will only be tried on a particular -interface. When the client receives a lease from a server, it always +is valid. If set, this lease will only be tried on a particular +interface. When the client receives a lease from a server, it always records the interface number on which it received that lease. If predefined leases are specified in the dhclient.conf file, the interface should also be specified, although this is not required. @@ -413,15 +414,15 @@ interface should also be specified, although this is n .PP The .B fixed-address -statement is used to set the ip address of a particular lease. This -is required for all lease statements. The IP address must be +statement is used to set the ip address of a particular lease. This +is required for all lease statements. The IP address must be specified as a dotted quad (e.g., 12.34.56.78). .PP \fBfilename "\fR\fIstring\fR\fB";\fR .PP The .B filename -statement specifies the name of the boot filename to use. This is +statement specifies the name of the boot filename to use. This is not used by the standard client configuration script, but is included for completeness. .PP @@ -429,7 +430,7 @@ for completeness. .PP The .B server-name -statement specifies the name of the boot server name to use. This is +statement specifies the name of the boot server name to use. This is also not used by the standard client configuration script. .PP \fBoption\fR \fIoption-declaration\fR\fB;\fR @@ -449,9 +450,9 @@ statement is used to specify the pathname of the dhcp configuration script. This script is used by the dhcp client to set each interface's initial configuration prior to requesting an address, to test the address once it has been offered, and to set the -interface's final configuration once a lease has been acquired. If +interface's final configuration once a lease has been acquired. If no lease is acquired, the script is used to test predefined leases, if -any, and also called once if no valid lease can be identified. For +any, and also called once if no valid lease can be identified. For more information, see .B dhclient-script(8). .PP @@ -462,7 +463,7 @@ The statement is used to specify which option space should be used for decoding the vendor-encapsulate-options option if one is received. The \fIdhcp-vendor-identifier\fR can be used to request a specific -class of vendor options from the server. See +class of vendor options from the server. See .B dhcp-options(5) for details. .PP @@ -493,9 +494,9 @@ interface requires media type configuration. .PP The \fBrenew\fR statement defines the time at which the dhcp client should begin trying to contact its server to renew a lease that it is -using. The \fBrebind\fR statement defines the time at which the dhcp +using. The \fBrebind\fR statement defines the time at which the dhcp client should begin to try to contact \fIany\fR dhcp server in order -to renew its lease. The \fBexpire\fR statement defines the time at +to renew its lease. The \fBexpire\fR statement defines the time at which the dhcp client must stop using a lease if it has not been able to contact a server in order to renew it. .PP @@ -547,7 +548,7 @@ instead of an actual date. Some DHCP clients running TCP/IP roaming protocols may require that in addition to the lease they may acquire via DHCP, their interface also be configured with a predefined IP alias so that they can have a -permanent IP address even while roaming. The Internet Systems +permanent IP address even while roaming. The Internet Systems Consortium DHCP client doesn't support roaming with fixed addresses directly, but in order to facilitate such experimentation, the dhcp client can be set up to configure an IP alias using the @@ -559,7 +560,7 @@ options other than the subnet-mask option are ignored client configuration script, and expiry times are ignored. A typical alias declaration includes an interface declaration, a fixed-address declaration for the IP alias address, and a subnet-mask option -declaration. A medium statement should never be included in an alias +declaration. A medium statement should never be included in an alias declaration. .SH OTHER DECLARATIONS \fBdb-time-format\fR [ \fIdefault\fR | \fIlocal\fR ] \fB;\fR @@ -588,7 +589,6 @@ the subnet, counting the number of significant bits in from the leftmost end. Example configuration syntax: .PP .I \fIreject\fR 192.168.0.0\fB/\fR16\fB,\fR 10.0.0.5\fB;\fR -.RE .PP The above example would cause offers from any server identifier in the entire RFC 1918 "Class C" network 192.168.0.0/16, or the specific @@ -597,11 +597,11 @@ single address 10.0.0.5, to be rejected. \fBinterface "\fIname\fB" { \fIdeclarations ... \fB } .PP A client with more than one network interface may require different -behaviour depending on which interface is being configured. All +behaviour depending on which interface is being configured. All timing parameters and declarations other than lease and alias declarations can be enclosed in an interface declaration, and those parameters will then be used only for the interface that matches the -specified name. Interfaces for which there is no interface +specified name. Interfaces for which there is no interface declaration will use the parameters declared outside of any interface declaration, or the default settings. .PP @@ -622,11 +622,11 @@ Each interface that the DHCP client is supporting norm client state machine running on it to acquire and maintain its lease. A pseudo-interface is just another state machine running on the interface named \fIreal-name\fR, with its own lease and its own -state. If you use this feature, you must provide a client identifier +state. If you use this feature, you must provide a client identifier for both the pseudo-interface and the actual interface, and the two -identifiers must be different. You must also provide a separate +identifiers must be different. You must also provide a separate client script for the pseudo-interface to do what you want with the IP -address. For example: +address. For example: .PP .nf interface "ep0" { @@ -641,7 +641,7 @@ address. For example: The client script for the pseudo-interface should not configure the interface up or down - essentially, all it needs to handle are the states where a lease has been acquired or renewed, and the states -where a lease has expired. See \fBdhclient-script(8)\fR for more +where a lease has expired. See \fBdhclient-script(8)\fR for more information. .PP \fBmedia "\fImedia setup\fB"\fI [ \fB, "\fImedia setup\fB", \fI... ]\fB;\fR @@ -649,27 +649,27 @@ information. The .B media statement defines one or more media configuration parameters which may -be tried while attempting to acquire an IP address. The dhcp client +be tried while attempting to acquire an IP address. The dhcp client will cycle through each media setup string on the list, configuring the interface using that setup and attempting to boot, and then trying -the next one. This can be used for network interfaces which aren't +the next one. This can be used for network interfaces which aren't capable of sensing the media type unaided - whichever media type succeeds in getting a request to the server and hearing the reply is probably right (no guarantees). .PP The media setup is only used for the initial phase of address -acquisition (the DHCPDISCOVER and DHCPOFFER packets). Once an +acquisition (the DHCPDISCOVER and DHCPOFFER packets). Once an address has been acquired, the dhcp client will record it in its lease database and will record the media type used to acquire the address. Whenever the client tries to renew the lease, it will use that same -media type. The lease must expire before the client will go back to +media type. The lease must expire before the client will go back to cycling through media types. .SH SAMPLE The following configuration file is used on a laptop running NetBSD -1.3. The laptop has an IP alias of 192.5.5.213, and has one -interface, ep0 (a 3com 3C589C). Booting intervals have been +1.3. The laptop has an IP alias of 192.5.5.213, and has one +interface, ep0 (a 3com 3C589C). Booting intervals have been shortened somewhat from the default, because the client is known to -spend most of its time on networks with little DHCP activity. The +spend most of its time on networks with little DHCP activity. The laptop does roam to multiple networks. .nf @@ -701,7 +701,7 @@ alias { } .fi This is a very complicated dhclient.conf file - in general, yours -should be much simpler. In many cases, it's sufficient to just +should be much simpler. In many cases, it's sufficient to just create an empty dhclient.conf file - the defaults are usually fine. .SH SEE ALSO dhcp-options(5), dhcp-eval(5), dhclient.leases(5), dhcpd(8), dhcpd.conf(5), @@ -709,7 +709,7 @@ RFC2132, RFC2131. .SH AUTHOR .B dhclient(8) was written by Ted Lemon -under a contract with Vixie Labs. Funding +under a contract with Vixie Labs. Funding for this project was provided by Internet Systems Consortium. Information about Internet Systems Consortium can be found at .B https://www.isc.org.