find blocks in 103/8 that has not been allocated

apnic-unallocated.sh

# get ipv4 allocation records from rex.apnic.net
# rename it to apnic_ipv4.csv

grep -o ',"103.\+","2."' apnic_ipv4.csv | sed 's/,"//' | sed 's/","/\//' | sed 's/"$//' | sort -t . -k 1,1n -k 2,2n -k 3,3n | gawk -F '.' '{ printf "0x%x%s\n", lshift($2, 8) + $3, $4}' | sed 's/0\//\//' | gawk --non-decimal-data -F '/' '{ for (i = 1; i <= lshift(1, 24-$2); i++) printf "%d\n", $1+i-1 }' > final

seq 0x100 0xffff > total

diff --side-by-side --suppress-common-lines total final | gawk '{ printf "%x\n",lshift(103,24) + lshift($1,8) }' | gawk --non-decimal-data '{for (i=1;i<=NF;i++) printf "%d%s","0x"$i,(i==NF?"\n":".")}' FPAT='..' | sed 's/$/\/24/' > unallocated_ip.txt