Using bash to generate random IPs Issue

Question

I have a list of URL and I'm trying construct a firewall log with that list. Example:

$ cat urls.csv 

a.com

I know how to construct the log with IP directly mentioned as variable.

$ cat processor.sh 

#!/bin/bash
filename="$1"
while read -r line
do
   URLS="$line"
   IP='10.109.1.1'
   today_date=`date +%d/%b/%Y`
   conact_1=" - - ["
   concat_2=":00:00:00 +0000] "
   date_concat=$conact_1$today_date$concat_2
   GET='"GET '
   protocol=' HTTP/1.1" 304 0 304 0 0 0 655 456 645 368 0'
   final_url=$IP$conact_1$today_date$concat_2$GET$URLS$protocol
   echo $final_url
done < "$filename"

Result:

$ bash processor.sh urls.csv

10.109.1.1 - - [22/Jul/2018:00:00:00 +0000] "GET a.com HTTP/1.1" 304 0 304 0 0 0 655 456 645 368 0

Now If i have a log line of 50 or 100 or even more , How can I generate random IP for the total number of URLs and generate a log line ?

$cat urls.csv

a.com
b.com
c.com
d.com
....

Any suggestions on how to generate random IPs in bash?

Expected Result:

$ bash processor.sh urls.csv

1.1.1.1 - - [22/Jul/2018:00:00:00 +0000] "GET a.com HTTP/1.1" 304 0 304 0 0 0 655 456 645 368 0
1.1.1.2 - - [22/Jul/2018:00:00:00 +0000] "GET b.com HTTP/1.1" 304 0 304 0 0 0 655 456 645 368 0
1.1.1.3 - - [22/Jul/2018:00:00:00 +0000] "GET c.com HTTP/1.1" 304 0 304 0 0 0 655 456 645 368 0
1.1.1.4 - - [22/Jul/2018:00:00:00 +0000] "GET d.com HTTP/1.1" 304 0 304 0 0 0 655 456 645 368 0
............

date_concat=$(date +" - - [%d/%b/%Y:00:00:00 +0000] "); the format string isn't restricted to the special escape characters. — chepner
– chepner, Commented Jul 22, 2018 at 18:12

Joaquin · Accepted Answer · 2018-07-22 22:28:19Z

12

For IPv4, the basics would be:

printf "%d.%d.%d.%d\n" "$((RANDOM % 256))" "$((RANDOM % 256))" "$((RANDOM % 256))" "$((RANDOM % 256))"

You'll probably want to filter out 192.168.0.0/16 and 10.0.0.0/8 and a lot of other addresses. For IPv6, you might try:

for ((i=0;i<8;i++)); do printf "%02x%02x:" $((RANDOM%256)) $((RANDOM%256)); done | sed 's/:$//'

($RANDOM only generates values up to 2^15-1, so $((RANDOM%65536)) is pointless)

edited Jul 22, 2018 at 22:28

Joaquin

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answered Jul 22, 2018 at 12:49

William Pursell

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1 Comment

Inder Over a year ago

perhaps one need to do printf "%d.%d.%d.%d\n" "$((RANDOM % 256 ))" "$((RANDOM % 256 ))" "$((RANDOM % 256 ))" "$((RANDOM % 256 ))"

Arun · Accepted Answer · 2018-07-22 13:09:51Z

2

Works as expected based on Inder's answer.

$cat processor.sh

#!/bin/bash
filename="$1"
while read -r line
do
   URLS="$line"
   #IP=$(printf "%d.%d.%d.%d\n" "$((RANDOM % 256 ))")
   IP=$(printf "%d.%d.%d.%d\n" "$((RANDOM % 256 ))" "$((RANDOM % 256 ))" "$((RANDOM % 256 ))" "$((RANDOM % 256 ))")
   #IP='10.109.1.1'
   today_date=`date +%d/%b/%Y`
   conact_1=" - - ["
   concat_2=":00:00:00 +0000] "
   date_concat=$conact_1$today_date$concat_2
   GET='"GET '
   protocol=' HTTP/1.1" 304 0 304 0 0 0 655 456 645 368 0'
   final_url=$IP$conact_1$today_date$concat_2$GET$URLS$protocol
   echo $final_url
done < "$filename"

$ bash processor.sh input.csv
103.137.94.111 - - [22/Jul/2018:00:00:00 +0000] "GET a.com HTTP/1.1" 304 0 304 0 0 0 655 456 645 368 0
74.123.232.234 - - [22/Jul/2018:00:00:00 +0000] "GET b.com HTTP/1.1" 304 0 304 0 0 0 655 456 645 368 0
102.13.8.154 - - [22/Jul/2018:00:00:00 +0000] "GET c.com HTTP/1.1" 304 0 304 0 0 0 655 456 645 368 0
210.106.160.230 - - [22/Jul/2018:00:00:00 +0000] "GET d.com HTTP/1.1" 304 0 304 0 0 0 655 456 645 368 0

answered Jul 22, 2018 at 13:09

Arun

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1 Comment

Inder Over a year ago

I just did a minor correction its still williams answer and credits :)

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