Perl Regular expression for IP address range - regex

Question

I have some internet traffic data to analyze. I need to analyze only those packets that are within a certain IP range. So, I need to write a if statement. I suppose I need a regular expression for the test condition. My knowledge of regexp is a little weak. Can someone tell me how would I construct a regular expression for that condition. An example range may be like
Group A
56.286.75.0/19
57.256.106.0/21
64.131.14.0/22
Group B
58.176.44.0/21
58.177.92.0/19
The if statement would be like
if("IP in A" || "IP in B") {
do something
}
else { do something else }
so i would need to make the equivalent regexp for "IP in A" and "IP in B" conditions.

Answer 1

I don't think that regexps provide much advantage for this problem.
Instead, use the Net::Netmask module. The "match" method should do what you want.

Answer 2

I have to echo the disagreement with using a regex to check IP addresses...however, here is a way to pull IPs out of text:
qr{
(?<!\d) # No digit having come immediately before
(?: [1-9] \d? # any one or two-digit number
| 1 \d \d # OR any three-digit number starting with 1
| 2 (?: [0-4] \d # OR 200 - 249
| 5 [0-6] # OR 250 - 256
)
)
(?: \. # followed by a dot
(?: [1-9] \d? # 1-256 reprise...
| 1 \d \d
| 2 (?: [0-4 \d
| 5 [0-6]
)
)
){3} # that group exactly 3 times
(?!\d) # no digit following immediately after
}x
;
But given that general pattern, we can construct an IP parser. But for the given "ranges", I wouldn't do anything less than the following:
A => qr{
(?<! \d )
(?: 56\.186\. 75
| 57\.256\.106
| 64\.131\. 14
)
\.
(?: [1-9] \d?
| 1 \d \d
| 2 (?: [0-4] \d
| 5 [0-6]
)
)
(?! \d )
}x
B => qr{
(?<! \d )
58 \.
(?: 176\.44
| 177\.92
)
\.
(?: [1-9] \d?
| 1 \d \d
| 2 (?: [0-4] \d
| 5 [0-6]
)
)
(?! \d )
}x

Answer 3

I'm doing something like:
use NetAddr::IP;
my #group_a = map NetAddr::IP->new($_), #group_a_masks;
...
my $addr = NetAddr::IP->new( $ip_addr_in );
if ( grep $_->contains( $addr ), #group_a ) {
print "group a";
}
I chose NetAddr::IP over Net::Netmask for IPv6 support.

Answer 4

Martin is right, use Net::Netmask. If you really want to use a regex though...
$prefix = "192.168.1.0/25";
$ip1 = "192.168.1.1";
$ip2 = "192.168.1.129";
$prefix =~ s/([0-9]+)\.([0-9]+)\.([0-9]+)\.([0-9]+)\/([0-9]+)/$mask=(2**32-1)<<(32-$5); $1<<24|$2<<16|$3<<8|$4/e;
$ip1 =~ s/([0-9]+)\.([0-9]+)\.([0-9]+)\.([0-9]+)/$1<<24|$2<<16|$3<<8|$4/e;
$ip2 =~ s/([0-9]+)\.([0-9]+)\.([0-9]+)\.([0-9]+)/$1<<24|$2<<16|$3<<8|$4/e;
if (($prefix & $mask) == ($ip1 & $mask)) {
print "ip1 matches\n";
}
if (($prefix & $mask) == ($ip2 & $mask)) {
print "ip2 matches\n";
}