DHCP Commands

The following table lists the commands that you can use to manage DHCP on your network.

Table 18-1 Commands Used in DHCP

Command	Description	Man Page
dhtadm	Used to make changes to the options and macros in the dhcptab. This command is most useful in scripts that you create to automate changes to your DHCP information. Use dhtadm with the -P option, and pipe the output through the grep command for a quick way to search for particular option values in the dhcptab table.	dhtadm(1M)
pntadm	Used to make changes to the DHCP network tables that map client IDs to IP addresses and optionally associate configuration information with IP addresses.	pntadm(1M)
dhcpconfig	Used to configure and unconfigure DHCP servers and BOOTP relay agents. Also used to convert to a different data store format, and to import and export DHCP configuration data.	dhcpconfig(1M)
in.dhcpd	The DHCP server daemon. The daemon is started when the system is started. You should not start the server daemon directly. Use DHCP Manager, the svcadm command, or dhcpconfig to start and stop the daemon. The daemon should be invoked directly only to run the server in debug mode to troubleshoot problems.	in.dhcpd(1M)
dhcpmgr	The DHCP Manager, a graphical user interface (GUI) tool used to configure and manage the DHCP service. DHCP Manager is the recommended Solaris DHCP management tool.	dhcpmgr(1M)
ifconfig	Used at system boot to assign IP addresses to network interfaces, configure network interface parameters, or both. On a Solaris DHCP client, ifconfig starts DHCP to get the parameters (including the IP address) needed to configure a network interface.	ifconfig(1M)
dhcpinfo	Used by system startup scripts on Solaris client systems to obtain information (such as the host name) from the DHCP client daemon, dhcpagent. You can also use dhcpinfo in scripts or at the command line to obtain specified parameter values.	dhcpinfo(1)
snoop	Used to capture and display the contents of packets being passed across the network. snoop is useful for troubleshooting problems with the DHCP service.	snoop(1M)
dhcpagent	The DHCP client daemon, which implements the client side of the DHCP protocol.	dhcpagent(1M)

Running DHCP Commands in Scripts

The dhcpconfig, dhtadm, and pntadm commands are optimized for use in scripts. In particular, the pntadm command is useful for creating a large number of IP address entries in a DHCP network table. The following sample script uses pntadm in batch mode to create IP addresses.

Example 18-1 addclient.ksh Script With the pntadm Command

#! /usr/bin/ksh
#
# This script utilizes the pntadm batch facility to add client entries
# to a DHCP network table. It assumes that the user has the rights to
# run pntadm to add entries to DHCP network tables.

#
# Based on the nsswitch setting, query the netmasks table for a netmask.
# Accepts one argument, a dotted IP address.
#
get_netmask()
{
    MTMP=`getent netmasks ${1} | awk '{ print $2 }'`
    if [ ! -z "${MTMP}" ]
    then
        print - ${MTMP}
    fi
}

#
# Based on the network specification, determine whether or not network is 
# subnetted or supernetted.
# Given a dotted IP network number, convert it to the default class
# network.(used to detect subnetting). Requires one argument, the
# network number. (e.g. 10.0.0.0) Echos the default network and default
# mask for success, null if error.
#
get_default_class()
{
    NN01=${1%%.*}
    tmp=${1#*.}
    NN02=${tmp%%.*}
    tmp=${tmp#*.}
    NN03=${tmp%%.*}
    tmp=${tmp#*.}
    NN04=${tmp%%.*}
    RETNET=""
    RETMASK=""

    typeset -i16 ONE=10#${1%%.*}
    typeset -i10 X=$((${ONE}&16#f0))
    if [ ${X} -eq 224 ]
    then
        # Multicast
        typeset -i10 TMP=$((${ONE}&16#f0))
        RETNET="${TMP}.0.0.0"
        RETMASK="240.0.0.0"
    fi
    typeset -i10 X=$((${ONE}&16#80))
    if [ -z "${RETNET}" -a ${X} -eq 0 ]
    then
        # Class A
        RETNET="${NN01}.0.0.0"
        RETMASK="255.0.0.0"
    fi
    typeset -i10 X=$((${ONE}&16#c0))
    if [ -z "${RETNET}" -a ${X} -eq 128 ]
    then
        # Class B
        RETNET="${NN01}.${NN02}.0.0"
        RETMASK="255.255.0.0"
    fi
    typeset -i10 X=$((${ONE}&16#e0))
    if [ -z "${RETNET}" -a ${X} -eq 192 ]
    then
        # Class C
        RETNET="${NN01}.${NN02}.${NN03}.0"
        RETMASK="255.255.255.0"
    fi
    print - ${RETNET} ${RETMASK}
    unset NNO1 NNO2 NNO3 NNO4 RETNET RETMASK X ONE
}

#
# Given a dotted form of an IP address, convert it to its hex equivalent.
#
convert_dotted_to_hex()
{
    typeset -i10 one=${1%%.*}
    typeset -i16 one=${one}
    typeset -Z2 one=${one}
    tmp=${1#*.}

    typeset -i10 two=${tmp%%.*}
    typeset -i16 two=${two}
    typeset -Z2 two=${two}
    tmp=${tmp#*.}

    typeset -i10 three=${tmp%%.*}
    typeset -i16 three=${three}
    typeset -Z2 three=${three}
    tmp=${tmp#*.}

    typeset -i10 four=${tmp%%.*}
    typeset -i16 four=${four}
    typeset -Z2 four=${four}

     hex=`print - ${one}${two}${three}${four} | sed -e 's/#/0/g'`
     print - 16#${hex}
     unset one two three four tmp
}

#
# Generate an IP address given the network address, mask, increment.
# 
get_addr()
{
    typeset -i16 net=`convert_dotted_to_hex ${1}`
    typeset -i16 mask=`convert_dotted_to_hex ${2}`
    typeset -i16 incr=10#${3}

    # Maximum legal value - invert the mask, add to net.
    typeset -i16 mhosts=~${mask}
    typeset -i16 maxnet=${net}+${mhosts}

    # Add the incr value.
    let net=${net}+${incr}

    if [ $((${net} < ${maxnet})) -eq 1 ]
    then
        typeset -i16 a=${net}\&16#ff000000
        typeset -i10 a="${a}>>24"

        typeset -i16 b=${net}\&16#ff0000
        typeset -i10 b="${b}>>16"

        typeset -i16 c=${net}\&16#ff00
        typeset -i10 c="${c}>>8"

        typeset -i10 d=${net}\&16#ff
        print - "${a}.${b}.${c}.${d}"
    fi
    unset net mask incr mhosts maxnet a b c d
}

# Given a network address and client address, return the index.
client_index()
{
    typeset -i NNO1=${1%%.*}
    tmp=${1#*.}
    typeset -i NNO2=${tmp%%.*}
    tmp=${tmp#*.}
    typeset -i NNO3=${tmp%%.*}
    tmp=${tmp#*.}
    typeset -i NNO4=${tmp%%.*}

    typeset -i16 NNF1
    let NNF1=${NNO1}
    typeset -i16 NNF2
    let NNF2=${NNO2}
    typeset -i16 NNF3
    let NNF3=${NNO3}
    typeset -i16 NNF4
    let NNF4=${NNO4}
    typeset +i16 NNF1
    typeset +i16 NNF2
    typeset +i16 NNF3
    typeset +i16 NNF4
    NNF1=${NNF1#16\#}
    NNF2=${NNF2#16\#}
    NNF3=${NNF3#16\#}
    NNF4=${NNF4#16\#}
    if [ ${#NNF1} -eq 1 ]
    then
        NNF1="0${NNF1}"
    fi
    if [ ${#NNF2} -eq 1 ]
    then
        NNF2="0${NNF2}"
    fi
    if [ ${#NNF3} -eq 1 ]
    then
        NNF3="0${NNF3}"
    fi
    if [ ${#NNF4} -eq 1 ]
    then
        NNF4="0${NNF4}"
    fi
    typeset -i16 NN
    let NN=16#${NNF1}${NNF2}${NNF3}${NNF4}
    unset NNF1 NNF2 NNF3 NNF4

    typeset -i NNO1=${2%%.*}
    tmp=${2#*.}
    typeset -i NNO2=${tmp%%.*}
    tmp=${tmp#*.}
    typeset -i NNO3=${tmp%%.*}
    tmp=${tmp#*.}
    typeset -i NNO4=${tmp%%.*}
    typeset -i16 NNF1
    let NNF1=${NNO1}
    typeset -i16 NNF2
    let NNF2=${NNO2}
    typeset -i16 NNF3
    let NNF3=${NNO3}
    typeset -i16 NNF4
    let NNF4=${NNO4}
    typeset +i16 NNF1
    typeset +i16 NNF2
    typeset +i16 NNF3
    typeset +i16 NNF4
    NNF1=${NNF1#16\#}
    NNF2=${NNF2#16\#}
    NNF3=${NNF3#16\#}
    NNF4=${NNF4#16\#}
    if [ ${#NNF1} -eq 1 ]
    then
        NNF1="0${NNF1}"
    fi
    if [ ${#NNF2} -eq 1 ]
    then
        NNF2="0${NNF2}"
    fi
    if [ ${#NNF3} -eq 1 ]
    then
        NNF3="0${NNF3}"
    fi
    if [ ${#NNF4} -eq 1 ]
    then
        NNF4="0${NNF4}"
    fi
    typeset -i16 NC
    let NC=16#${NNF1}${NNF2}${NNF3}${NNF4}
    typeset -i10 ANS
    let ANS=${NC}-${NN}
    print - $ANS
}

#
# Check usage.
#
if [ "$#" != 3 ]
then
    print "This script is used to add client entries to a DHCP network"
    print "table by utilizing the pntadm batch facilty.\n"
    print "usage: $0 network start_ip entries\n"
    print "where: network is the IP address of the network"
        print "       start_ip is the starting IP address \n"
        print "       entries is the number of the entries to add\n"
    print "example: $0 10.148.174.0 10.148.174.1 254\n"
    return
fi

#
# Use input arguments to set script variables.
#
NETWORK=$1
START_IP=$2
typeset -i STRTNUM=`client_index ${NETWORK} ${START_IP}`
let ENDNUM=${STRTNUM}+$3
let ENTRYNUM=${STRTNUM}
BATCHFILE=/tmp/batchfile.$$
MACRO=`uname -n`

#
# Check if mask in netmasks table. First try
# for network address as given, in case VLSM
# is in use.
#
NETMASK=`get_netmask ${NETWORK}`
if [ -z "${NETMASK}" ]
then
    get_default_class ${NETWORK} | read DEFNET DEFMASK
    # use the default.
    if [ "${DEFNET}" != "${NETWORK}" ]
    then
        # likely subnetted/supernetted.
        print - "\n\n###\tWarning\t###\n"
        print - "Network ${NETWORK} is netmasked, but no entry was found  \n
              in the 'netmasks' table; please update the 'netmasks'  \n
              table in the appropriate nameservice before continuing. \n 
              (See /etc/nsswitch.conf.) \n" >&2
        return 1
    else
        # use the default.
        NETMASK="${DEFMASK}"
    fi
fi

#
# Create a batch file.
#
print -n "Creating batch file "
while [ ${ENTRYNUM} -lt ${ENDNUM} ]
do
    if [ $((${ENTRYNUM}-${STRTNUM}))%50 -eq 0 ]
    then
        print -n "."
    fi

    CLIENTIP=`get_addr ${NETWORK} ${NETMASK} ${ENTRYNUM}`
    print "pntadm -A ${CLIENTIP} -m ${MACRO} ${NETWORK}" >> ${BATCHFILE}
    let ENTRYNUM=${ENTRYNUM}+1
done
print " done.\n"

#
# Run pntadm in batch mode and redirect output to a temporary file.
# Progress can be monitored by using the output file.
#
print "Batch processing output redirected to ${BATCHFILE}"
print "Batch processing started."

pntadm -B ${BATCHFILE} -v > /tmp/batch.out 2 >&1

print "Batch processing completed."