Created
December 8, 2016 19:17
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Bash script for calculating network and broadcast addresses from ip and netmask or CIDR Notation
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#!/bin/bash | |
# Calculates network and broadcast based on supplied ip address and netmask | |
# Usage: broadcast_calc.sh 192.168.0.1 255.255.255.0 | |
# Usage: broadcast_calc.sh 192.168.0.1/24 | |
tonum() { | |
if [[ $1 =~ ([[:digit:]]+)\.([[:digit:]]+)\.([[:digit:]]+)\.([[:digit:]]+) ]]; then | |
addr=$(( (${BASH_REMATCH[1]} << 24) + (${BASH_REMATCH[2]} << 16) + (${BASH_REMATCH[3]} << 8) + ${BASH_REMATCH[4]} )) | |
eval "$2=\$addr" | |
fi | |
} | |
toaddr() { | |
b1=$(( ($1 & 0xFF000000) >> 24)) | |
b2=$(( ($1 & 0xFF0000) >> 16)) | |
b3=$(( ($1 & 0xFF00) >> 8)) | |
b4=$(( $1 & 0xFF )) | |
eval "$2=\$b1.\$b2.\$b3.\$b4" | |
} | |
if [[ $1 =~ ^([0-9\.]+)/([0-9]+)$ ]]; then | |
# CIDR notation | |
IPADDR=${BASH_REMATCH[1]} | |
NETMASKLEN=${BASH_REMATCH[2]} | |
zeros=$((32-NETMASKLEN)) | |
NETMASKNUM=0 | |
for (( i=0; i<$zeros; i++ )); do | |
NETMASKNUM=$(( (NETMASKNUM << 1) ^ 1 )) | |
done | |
NETMASKNUM=$((NETMASKNUM ^ 0xFFFFFFFF)) | |
toaddr $NETMASKNUM NETMASK | |
else | |
IPADDR=${1:-192.168.1.1} | |
NETMASK=${2:-255.255.255.0} | |
fi | |
tonum $IPADDR IPADDRNUM | |
tonum $NETMASK NETMASKNUM | |
#printf "IPADDRNUM: %x\n" $IPADDRNUM | |
#printf "NETMASKNUM: %x\n" $NETMASKNUM | |
# The logic to calculate network and broadcast | |
INVNETMASKNUM=$(( 0xFFFFFFFF ^ NETMASKNUM )) | |
NETWORKNUM=$(( IPADDRNUM & NETMASKNUM )) | |
BROADCASTNUM=$(( INVNETMASKNUM | NETWORKNUM )) | |
IPADDRBIN=$( python -c "print(bin(${IPADDRNUM} )[2:].zfill(32))") | |
NETMASKBIN=$( python -c "print(bin(${NETMASKNUM} )[2:].zfill(32))") | |
NETWORKBIN=$( python -c "print(bin(${NETWORKNUM} )[2:].zfill(32))") | |
BROADCASTBIN=$(python -c "print(bin(${BROADCASTNUM})[2:].zfill(32))") | |
toaddr $NETWORKNUM NETWORK | |
toaddr $BROADCASTNUM BROADCAST | |
printf "%-25s %s\n" "IPADDR=$IPADDR" $IPADDRBIN | |
printf "%-25s %s\n" "NETMASK=$NETMASK" $NETMASKBIN | |
printf "%-25s %s\n" "NETWORK=$NETWORK" $NETWORKBIN | |
printf "%-25s %s\n" "BROADCAST=$BROADCAST" $BROADCASTBIN |
I needed something to +1 an IP address, so the tonum and toaddr were perfect, thx :-)
Awesome !
You saved me. When setting up a network bridge with iproute2, you have to manually enter the the broadcast address. Thanks to you it's now calculated from the ip and subnet mask.
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GREAT WORK