Here is a script that is intended to generate a series of IPv4 addresses in
CIDR/16 address space:
counter=1
while [ $counter -le 4096 ]
do prefix=185.180; dd if=/dev/urandom bs=2 count=1 2>/dev/null | od -An -tu1
| tr -s ' ' . | sed s/^/$prefix/ >> Temp42120Works.txt
((counter++))
done
The script produces a list of 4,096 IPv4 addresses, each of which starts with
185.180, in about
ten seconds. It works OK in the Mate terminal, but not when I invoke bash
(/bin/sh), which doesn't
like counter++ and fails to stop generating IPv4 addresses as a result.
The following code is an effort to expand the scope of the task to encompass
an entire list of
differently prefixed addresses:
retnuoc=0
while [ "retnuoc" -le 26 ]
do NUM=$(`expr $retnuoc + 1`)
counter=1
while [ "$counter" -le 4 ]
prefix=`expr tail -n+$NUM SS.IPv4-NLU-January2020-26Prefixes.txt | head -n1`;
dd if=/dev/urandom bs=2 count=1 2>/dev/null | od -An -tu1 | tr -s ' ' . | sed
s/^/$prefix/ >> Temp41921F13.txt
counter=$(`expr $counter + 1`)
done
retnuoc=$(`expr $retnuocm+ 1`)
done
The first two octets are contained in the file
SS.IPv4-NLU-January2020-26Prefixes.txt (attached)
and extracted with the expression
tail -n+NUM SS.IPv4-NLU-January2020-26Prefixes.txt | head -n1
which works OK when NUM is replaced by a number between 1 and 26 (in the
present example).
The second pair of octets is randomly generated with this expression wherein
$NUM is replaced by an
exemplar octet pair:
prefix=185.39; dd if=/dev/urandom bs=2 count=1 2>/dev/null | od -An -tu1 | tr
-s ' ' . | sed s/^/$prefix/
Alas, progress has stalled now that the script no longer produces complaints
of syntax errors.
If it were to work, 104 IPv4 addresses would be forthcoming, four for each of
the twenty six
octet pairs.
George Langford
99.79
99.192
98.25
98.187
98.162
97.107
96.9
96.44
96.30
96.2
96.114
95.90
95.86
95.85
95.84
95.80
95.73
95.72
95.71
95.70
95.67
95.66
95.64
95.58
95.47
95.46
