ref: 21947578303cdb0fcb4b0cdfe80aa9dab5f6b447
dir: /man/8/dhcp/
.TH DHCP 8
.SH NAME
dhcp \- configure network interface details using DHCP
.SH SYNOPSIS
.B ip/dhcp
[
.B -bdmpr
] [
.BI -g " gateway"
] [
.BI -h " hostname"
] [
.BI -x " net
]
.I ifcdir
[
.I localip
[
.I localmask
]]
.SH DESCRIPTION
.I Dhcp
uses the Dynamic Host Configuration Protocol (DHCP) to configure the
.IR ip (3)
interface represented by
.I ifcdir
(eg,
.BR /net/ipifc/1 ).
The interface must have a device already bound to it.
.I Dhcp
uses the MAC address of that device in its requests.
.PP
.I Dhcp
broadcasts a DHCP request for an address and various network parameters.
It takes the first acceptable offer, sets the interface to that address, and writes the address and
parameter values, in
.IR ndb (6)
format, to
.BR /net/ndb ,
where
.IR cs (8),
.IR dns (8)
and others will find them.
If the address is provided with a limited lease,
.I dhcp
itself returns, but it leaves
a process in the background that periodically renews the lease (or requests a new address if the lease is not renewed).
.PP
If
.I localip
is given,
.I dhcp
attempts to reacquire that address.
If successful, it configures the interface with that address (and mask if supplied),
maintaining any lease as before.
If it cannot reacquire the address, it broadcasts a request for a new address, as above.
.PP
The options are:
.TP
.B -b
Use plain BOOTP without the DHCP options
.TP
.B -d
Enable debugging output on standard output
.TP
.BI -g " gateway"
Suggest
.I gateway
as the default gateway (the server might change it)
.TP
.BI -h " hostname"
Use
.I hostname
as the current host's name in DHCP messages
.TP
.B -m
Monitor the DHCP status and print a summary on standard output whenever it changes
.TP
.B -n
Do not configure the interface
.TP
.B -p
Print the resulting configuration on standard output
.TP
.B -r
Retry DHCP periodically until it succeeds
.TP
.BI -x " net"
Use mount point
.I net
to access the network,
and write the results to
.IB net /ndb
(default:
.BR /net )
.PD
.SH EXAMPLE
Allocate a new interface, bind an ether device to it, and configure it with
.IR dhcp :
.IP
.EX
x=`{cat /net/ipifc/clone}
echo bind ether /net/ether0 >/net/ipifc/$x/ctl &&
ip/dhcp /net/ipifc/$x
.EE
.SH SOURCE
.B /appl/cmd/ip/dhcp.b
.SH SEE ALSO
.IR ip (3),
.IR ndb (6),
.IR cs (8),
.IR dns (8)
.SH DIAGNOSTICS
.I Dhcp
returns an error status if it receives no acceptable reply, unless the
.B -r
option is given to force retries.