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patlegu/broadcast_calc.sh

Forked from cskeeters/broadcast_calc.sh
Created May 2, 2025 07:29
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  1. @cskeeters cskeeters created this gist Dec 8, 2016.
    61 changes: 61 additions & 0 deletions broadcast_calc.sh
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,61 @@
    #!/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