Generate all possible ipv4 addresses using seq? - bash

Question

When using seq to generate an ip address, I use seq 0 255 and it generate the last octet. How can I transition this so it will generate all the other octets and their possible combinations (over 4 million combinations). Any help to start would be appreciated

Answer 1

If you were looking for a bash solution:
for h in {1..255}; do for i in {1..255}; do for j in {1..255}; do for k in {1..255}; do echo "$h.$i.$j.$k"; done; done; done; done
Or the multi-line version
for h in {1..255}
do for i in {1..255}
do for j in {1..255}
do for k in {1..255}
do echo "$h.$i.$j.$k"
done
done
done
done
Or if you are really intent on using seq
for h in `seq 255`; do for i in `seq 255`; do for j in `seq 255`; do for k in `seq 255`; do echo "$h.$i.$j.$k"; done; done; done; done

Answer 2

With awk and four loops:
awk 'BEGIN{OFS="."; for(h=0;h<256;h++){for(i=0;i<256;i++){for(j=0;j<256;j++){for(k=0;k<256;k++){print h,i,j,k}}}}}'
With C and four loops:
Put this a file with name ipgen.c:
#include <stdio.h>
int main() {
int h, i, j, k;
for (h = 0; h < 256; h++) {
for (i = 0; i < 256; i++) {
for (j = 0; j < 256; j++) {
for (k = 0; k < 256; k++) {
printf("%d.%d.%d.%d\n", h, i, j, k);
}
}
}
}
return 0;
}
Compile it: gcc ipgen.c -o ipgen
Start it: ./ipgen

Answer 3

For speed I'd vote for a 4-way awk/for loop (per Cyrus comment), but thought I'd look at a recursive function:
tuple () {
local level=$1 # number of tuples to generate
local max=$2 # assume tuples are numbered 1 to max
local in=$3 # current tuple from parent
local pfx="." # for all but the topmost call we append a period on the front of our loop counter
[[ -z "${in}" ]] && pfx="" # topmost call appends no prefix
local i
local out
for (( i=1 ; i<=${max} ; i++ ))
do
out="${in}${pfx}${i}"
if [[ "${level}" -eq 1 ]] # if we've reached the bottom of our function calls
then
echo "${out}" # print our latest string
else
tuple $((level-1)) "${max}" "${out}" # otherwise recurse with the latest string
fi
done
}
To build a 3-tuple with values ranging from 1 to 2:
$ tuple 3 2
1.1.1
1.1.2
1.2.1
1.2.2
2.1.1
2.1.2
2.2.1
2.2.2
To build a 3-tuple with values ranging from 1 to 4:
$ tuple 3 4
1.1.1
1.1.2
1.1.3
1.1.4
1.2.1
...
4.3.4
4.4.1
4.4.2
4.4.3
4.4.4
To build a 4-tuple with values ranging from 1 to 255 (keep in mind this is NOT going to be fast since we're making a LOT of bash-level calls):
$ tuple 4 255
1.1.1.1
1.1.1.2
1.1.1.3
1.1.1.4
1.1.1.5
1.1.1.6
1.1.1.7
1.1.1.8
1.1.1.9
1.1.1.10
... if you let it run long enough ...
255.255.255.250
255.255.255.251
255.255.255.252
255.255.255.253
255.255.255.254
255.255.255.255