Comandos DHCP

En la tabla siguiente se enumeran los comandos que se pueden utilizar para gestionar DHCP en la red.

Tabla 18-1 Comandos utilizados en DHCP

Ejecución de comandos DHCP en secuencias

Los comandos dhcpconfig, dhtadm y pntadm están optimizados para su uso en secuencias. En particular, el comando pntadm es útil para crear una gran cantidad de entradas de dirección IP en una tabla de red DHCP. En la siguiente secuencia de ejemplo se utiliza pntadm en modo de proceso por lotes para crear direcciones IP.

Ejemplo 18-1 Secuencia addclient.ksh con el comando pntadm

#! /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 switch 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."