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diff --git a/relay/dhcrelay.8 b/relay/dhcrelay.8 new file mode 100644 index 0000000..a087d14 --- /dev/null +++ b/relay/dhcrelay.8 @@ -0,0 +1,258 @@ +.\" dhcrelay.8 +.\" +.\" Copyright (c) 2009-2011 by Internet Systems Consortium, Inc. ("ISC") +.\" Copyright (c) 2004,2007 by Internet Systems Consortium, Inc. ("ISC") +.\" Copyright (c) 1997-2003 by Internet Software Consortium +.\" +.\" Permission to use, copy, modify, and distribute this software for any +.\" purpose with or without fee is hereby granted, provided that the above +.\" copyright notice and this permission notice appear in all copies. +.\" +.\" THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES +.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF +.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR +.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES +.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN +.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT +.\" OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. +.\" +.\" Internet Systems Consortium, Inc. +.\" 950 Charter Street +.\" Redwood City, CA 94063 +.\" <info@isc.org> +.\" https://www.isc.org/ +.\" +.\" This software has been written for Internet Systems Consortium +.\" by Ted Lemon in cooperation with Vixie Enterprises. +.\" +.\" Support and other services are available for ISC products - see +.\" https://www.isc.org for more information or to learn more about ISC. +.\" +.\" $Id: dhcrelay.8,v 1.16.24.3 2011-04-15 22:12:50 sar Exp $ +.\" +.TH dhcrelay 8 +.SH NAME +dhcrelay - Dynamic Host Configuration Protocol Relay Agent +.SH SYNOPSIS +.B dhcrelay +[ +.B -4 +] +[ +.B -dqaD +] +[ +.B -p +.I port +] +[ +.B -c +.I count +] +[ +.B -A +.I length +] +[ +.B -pf +.I pid-file +] +[ +.B --no-pid +] +[ +.B -m +.I append +| +.I replace +| +.I forward +| +.I discard +] +[ +.B -i +.I interface0 +[ +.B ... +.B -i +.I interfaceN +] +] +.I server0 +[ +.I ...serverN +] +.PP +.B dhcrelay -6 +[ +.B -dqI +] +[ +.B -p +.I port +] +[ +.B -c +.I count +] +[ +.B -pf +.I pid-file +] +[ +.B --no-pid +] +.B -l +.I lower0 +[ +.B ... +.B -l +.I lowerN +] +.B -u +.I upper0 +[ +.B ... +.B -u +.I upperN +] +.SH DESCRIPTION +The Internet Systems Consortium DHCP Relay Agent, dhcrelay, provides a +means for relaying DHCP and BOOTP requests from a subnet to which +no DHCP server is directly connected to one or more DHCP servers on +other subnets. It supports both DHCPv4/BOOTP and DHCPv6 protocols. +.SH OPERATION +.PP +The DHCP Relay Agent listens for DHCPv4 or DHCPv6 queries from clients or +other relay agents on one or more interfaces, passing them along to +``upstream'' servers or relay agents as specified on the command line. +When a reply is received from upstream, it is multicast or unicast back +downstream to the source of the original request. +.SH COMMAND LINE +.PP +\fIProtocol selection options:\fR +.TP +-6 +Run dhcrelay as a DHCPv6 relay agent. Incompatible with the \fB-4\fR +option. +.TP +-4 +Run dhcrelay as a DHCPv4/BOOTP relay agent. This is the default mode of +operation, so the argument is not necessary, but may be specified for +clarity. Incompatible with \fB-6\fR. +.PP +\fISpecifying DHCPv4/BOOTP servers\fR +.PP +In DHCPv4 mode, a list of one or more server addresses must be specified on +the command line, to which DHCP/BOOTP queries should be relayed. +.PP +\fIOptions available for both DHCPv4 and DHCPv6:\fR +.TP +-c COUNT +Maximum hop count. When forwarding packets, dhcrelay discards packets +which have reached a hop count of COUNT. Default is 10. Maximum is 255. +.TP +-d +Force dhcrelay to run as a foreground process. Useful when running +dhcrelay under a debugger, or running out of inittab on System V systems. +.TP +-p PORT +Listen and transmit on port PORT. This is mostly useful for debugging +purposes. Default is port 67 for DHCPv4/BOOTP, or port 547 for DHCPv6. +.TP +-q +Quiet mode. Prevents dhcrelay6 from printing its network configuration +on startup. +.TP +-pf pid-file +Path to alternate pid file. +.TP +--no-pid +Option to disable writing pid files. By default the program +will write a pid file. +.PP +\fIOptions available in DHCPv4 mode only:\fR +.TP +-a +Append an agent option field to each request before forwarding it to +the server. Agent option fields in responses sent from servers to +clients will be stripped before forwarding such responses back to the +client. The agent option field will contain two agent options: the Circuit +ID suboption and the Remote ID suboption. Currently, the Circuit ID will +be the printable name of the interface on which the client request was +received. The client supports inclusion of a Remote ID suboption as well, +but this is not used by default. +.TP +-A LENGTH +Specify the maximum packet size to send to a DHCPv4/BOOTP server. This +might be done to allow sufficient space for addition of relay agent +options while still fitting into the Ethernet MTU size. +.TP +-D +Drop packets from upstream servers if they contain Relay Agent +Information options that indicate they were generated in response to +a query that came via a different relay agent. If this option is not +specified, such packets will be relayed anyway. +.TP +-i \fIifname\fR +Listen for DHCPv4/BOOTP queries on interface \fIifname\fR. Multiple +interfaces may be specified by using more than one \fB-i\fR option. If +no interfaces are specified on the command line, dhcrelay will identify +all network interfaces, eliminating non-broadcast interfaces if possible, +and attempt to listen on all of them. +.TP +-m \fIappend\fR|\fIreplace\fR|\fIforward\fR|\fIdiscard\fR +Control the handling of incoming DHCPv4 packets which already contain +relay agent options. If such a packet does not have \fIgiaddr\fR set in +its header, the DHCP standard requires that the packet be discarded. +However, if \fIgiaddr\fR is set, the relay agent may handle the situation +in four ways: It may \fIappend\fR its own set of relay options to the +packet, leaving the supplied option field intact; it may \fIreplace\fR the +existing agent option field; it may \fIforward\fR the packet unchanged; or, +it may \fIdiscard\fR it. +.PP +\fIOptions available in DHCPv6 mode only:\fR +.TP +-I +Force use of the DHCPv6 Interface-ID option. This option is +automatically sent when there are two or more downstream interfaces +in use, to disambiguate between them. The \fB-I\fR option causes +dhcrelay to send the option even if there is only one downstream +interface. +.TP +-l [\fIaddress%\fR]\fIifname\fR[\fI#index\fR] +Specifies the ``lower'' network interface for DHCPv6 relay mode: the +interface on which queries will be received from clients or from other +relay agents. At least one \fB-l\fR option must be included in the command +line when running in DHCPv6 mode. The interface name \fIifname\fR is a +mandatory parameter. The link address can be specified by \fIaddress%\fR; +if it isn't, dhcrelay will use the first non-link-local address configured +on the interface. The optional \fI#index\fR parameter specifies the +interface index. +.TP +-u [\fIaddress%\fR]\fIifname\fR +Specifies the ``upper'' network interface for DHCPv6 relay mode: the +interface to which queries from clients and other relay agents should be +forwarded. At least one \fB-u\fR option must be included in the command +line when running in DHCPv6 mode. The interface name \fIifname\fR is a +mandatory parameter. The destination unicast or multicast address can be +specified by \fIaddress%\fR; if not specified, the relay agent will forward +to the DHCPv6 \fIAll_DHCP_Relay_Agents_and_Servers\fR multicast address. +.PP +It is possible to specify the same interface with different addresses +more than once, and even, when the system supports it, to use the same +interface as both upper and lower interfaces. +.SH SEE ALSO +dhclient(8), dhcpd(8), RFC3315, RFC2132, RFC2131. +.SH BUGS +.PP +Using the same interface on both upper and lower sides may cause +loops, so when running this way, the maximum hop count should be set +to a low value. +.PP +The loopback interface is not (yet) recognized as a valid interface. +.SH AUTHOR +.B dhcrelay(8) +To learn more about Internet Systems Consortium, see +.B https://www.isc.org |