(bash) check if IP in subnet range file - regex

Question

I've a list of subnet range in a file:
2.32.0.0-2.47.255.255-255.240.0.0
2.112.0.0-2.119.255.255-255.248.0.0
2.156.0.0-2.159.255.255-255.252.0.0
2.192.0.0-2.199.255.255-255.248.0.0
...
(The file format is: {startip}-{endip}-{netmask})
I need check if an IP is included in one of the subnet in the file.

Answer 1

You may use awk for that:
echo '127.0.0.0-127.255.255.255-255.0.0.0' | awk -F- '
BEGIN { ip[1] = 127; ip[2] = 0; ip[3] = 0; ip[4] = 1; }
{ split($1, startIp, "."); split($2, endIp, ".");
for(i = 1; i <= 4; i++) {
if(ip[i] < int(startIp[i]) || ip[i] > int(endIp[i]))
break;
}
if(i == 5)
print "matching line: ", $0; }'
IP for searching is initially set as array in BEGIN-clause as array. Each line is compared in for-cycle and if each octet laying between startIp and endIp, "matching line" is printed.
Some Python 3 gibberish relying on ipaddress module from 3.3 (available for 2.6/2.7:
python3 -c 'from ipaddress import ip_address as IP; list(
map(print, ((startip, endip) for startip, endip, _ in
(ip.split("-") for ip in open("tmp/iplist.txt"))
if IP(startip) < IP("127.0.0.1") < IP(endip))))'
Which is actually one-liner version for following script:
import sys
from ipaddress import ip_address as IP
ip = IP(sys.argv[1])
with open(sys.argv[2]) as f:
for line in f:
startIp, endIp, _ = line.split('-')
if IP(startIp) < ip < IP(endIp):
print(line)
Which can be used like that:
$ python3 ipcheck.py 127.0.0.1 iplist.txt

Answer 2

Try this:
BEGIN {
FS="."
ex = "false"
split(address, ip, ".")
}
{
split($0, range, "[-.]")
for (i=1; i<5; i++) {
if (ip[i] < range[i] || ip[i] > range[i+4])
break;
else if ((ip[i] > range[i] && ip[i] < range[i+4]) || i == 4)
ex = "true"
}
}
END {
print ex
}
Invoke this awk script (checkIP.awk) like this:
$ awk -v address="2.156.0.5" -f checkIP.awk /path/to/ip/ranges/file
true
$ awk -v address="0.0.0.0" -f checkIP.awk /path/to/ip/ranges/file
false

Answer 3

You can use this awk script:
awk -F- -v arg='2.158.1.2' 'function ipval(arg) {
split(arg, arr, ".");
s=0;
for (i=1; i<=length(arr); i++)
s += arr[i] * (10**(6-i));
return s
}
ipval(arg) >= ipval($1) && ipval(arg) <= ipval($2)' file
2.156.0.0-2.159.255.255-255.252.0.0
ipval converts given ip address to a numeric value so that it can be compared easily using arithmetical operator.

Answer 4

Check if IP is valid and if it's on a local connection:
if ! ip route get ${ip} | grep -v via > /dev/null;then echo "bad IP";fi

Answer 5

I find this variant of the above script more useful:
function ipval()
{
RES=`awk -F- -v arg="$1" '{
split(arg, arr, ".");
s=0;
for (i=1; i<=length(arr); i++) { s += arr[i] * (256**(4-i)); }
print s
}' <<< '' `
return $RES
}
read -p "IP:" IP
ipval "$IP"
echo "RES=$RES"