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|
# ipnext: increment a dotted quad IP address
set -u
for i
do
INC=/bin/true
n="$i"
while $INC
do
# check that we have a dotted quad
if expr match "X$n" 'X[0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*$' >/dev/null
then
:
else
echo "\"$n\" isn't a dotted quad" >&2
exit 1
fi
# break out fields of dotted quad
q1=`expr match "X$n" 'X\([0-9][0-9]*\)\.[0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*$'`
q2=`expr match "X$n" 'X[0-9][0-9]*\.\([0-9][0-9]*\)\.[0-9][0-9]*\.[0-9][0-9]*$'`
q3=`expr match "X$n" 'X[0-9][0-9]*\.[0-9][0-9]*\.\([0-9][0-9]*\)\.[0-9][0-9]*$'`
q4=`expr match "X$n" 'X[0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*\.\([0-9][0-9]*\)$'`
# increment by 7.123.59.229 (arbitrary)
q1=`expr $q1 + 7`
q2=`expr $q2 + 123`
q3=`expr $q3 + 59`
q4=`expr $q4 + 229`
# perform carry
q1=`expr '(' $q1 + $q2 / 256 ')' % 256`
q2=`expr '(' $q2 + $q3 / 256 ')' % 256`
q3=`expr '(' $q3 + $q4 / 256 ')' % 256`
q4=`expr $q4 % 256`
# around again if unroutable address
n="$q1.$q2.$q3.$q4"
case "$n" in
10.*|192.168.*|172.16.[0-9].*|172.16.1[0-5].*|127.*)
;;
*) INC=/bin/false
esac
done
echo "$n"
done
|
