Using bash to generate random IPs Issue - bash

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
............

Answer 1

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)

Answer 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