shell 子網掩碼換算

#!/bin/ksh
#
# This script produces subnet number and broadcast address
# according to network number, subnet number and hosts number
# per subnet.
#
set -A network ${1//(\D)/ }
if [ $# -ne 3 ]; then
        echo
        echo Usage:  $0 netwok_number  subnet_number hosts_per_subnet
        echo
        echo For example:
        echo
        echo        "       $0 192.9.200.0  3 20"
        echo
        exit
fi
# Check the network number format
if [ ${#network[*]} -ne 4 ]; then
        echo Invalid network format
        exit
fi
# Check the network class invalidation
for (( i=0; i<=3; i++ )); do
        if [ ${network[$i]} -gt 255 ]; then
                echo Invalid network class.
                exit
        elif [ ${network[$i]} -ge 240 ]; then
                echo The network you input is a multicast address.
                exit
        fi
done
# Check the network class
if [ ${network[0]} -le 127 ]; then
        bits=24
elif [ ${network[0]} -ge 128 ]  && [ ${network[0]} -lt 192 ]; then
        bits=16
else
        bits=8
fi
# Get the bits needed for subnets and hosts
while true
do
if [ $((2**subnet)) -ge $2 ]; then
        break
else
        (( subnet++ ))
fi
done
while true
do
if [ $((2**subnet)) -ge $2 ]; then
        break
else
        (( subnet++ ))
fi
done
while true
do
if [ $((2**host - 2)) -ge $3 ]; then
        break
else
        (( host++ ))
fi
done
if [ $(( subnet + host )) -gt $bits ]; then
        echo Too many subnets or hosts in your configuration
        exit
fi
for (( i=31; i > (31 - host); i -- )); do
        net[$i]=0
done
for (( i=0; i <= (31 - host); i ++ )); do
        net[$i]=1
done
for (( l=0; l <= 7 ; l ++ )); do
        (( a[0] += (2**(7 - l) * net[l])))
        (( a[1] += (2**(7 - l) * net[l + 8])))
        (( a[2] += (2**(7 - l) * net[l + 16])))
        (( a[3] += (2**(7 - l) * net[l + 24])))
done
echo
echo Network prefix: $(( 32 - host ))
echo Network mask: ${a[0]}.${a[1]}.${a[2]}.${a[3]}
echo Total subnets: $(( 2**(bits - host)))
echo Hosts per subnet: $(( 2**host - 2))
echo
echo list $2 out of $(( 2**(bits - host))) subnets::
echo
for i in ${network[*]}
do
        j=7
        while [ $j -ge 0 ]
        do
          k=$((2**$j))
          if [ $(( $i & $k )) -eq $k ]; then
                net[n]=1
                broadcast[n]=1
          else
                net[n]=0
                broadcast[n]=0
          fi
          (( n ++ ))
          (( j -- ))
         done
done
for (( i=31; i > (31 - host); i -- )); do
        net[$i]=0
        broadcast[$i]=1
done
#for (( i=0; i < (2**subnet); i ++ )); do
for (( i=0; i < $2; i ++ )); do
        set -A a
        for (( j=0; j < subnet; j ++ )); do
          k=$((2**$j))
          if [ $(( $i & $k )) -eq $k ]; then
                net[$((32 - host - subnet + j))]=1
                broadcast[$((32 - host - subnet + j))]=1
          else
                net[$((32 - host - subnet + j))]=0
                broadcast[$((32 - host - subnet + j))]=0
          fi
        done
        for (( l=0; l <= 7 ; l ++ )); do
                (( a[0] += (2**(7 - l) * net[l])))
                (( a[1] += (2**(7 - l) * net[l + 8])))
                (( a[2] += (2**(7 - l) * net[l + 16])))
                (( a[3] += (2**(7 - l) * net[l + 24])))
                (( a[4] += (2**(7 - l) * broadcast[l])))
                (( a[5] += (2**(7 - l) * broadcast[l + 8])))
                (( a[6] += (2**(7 - l) * broadcast[l + 16])))
                (( a[7] += (2**(7 - l) * broadcast[l + 24])))
        done
        echo Network number: ${a[0]}.${a[1]}.${a[2]}.${a[3]} "      "  Broadcast address: ${a[4]}.${a[5]}.${a[6]}.${a[7]}
done