Win8 Strawberry 5.30.3.1 (64)  Wed 06/29/2022 21:31:05
C:\@Work\Perl\monks
>perl

use strict;
use warnings;

use Regexp::Common qw(net);

my $ip = 'csteppfw pts/0        2022-06-27 15:53 (192.168.5.100)';

($ip) = $ip =~ m{ (?<! \d) $RE{net}{IPv4} (?! \d) }xmsg;
print "'$ip' \n";

^Z
'192.168.5.100'

##</code><code>##

Win8 Strawberry 5.8.9.5 (32)  Wed 06/29/2022 23:13:52
C:\@Work\Perl\monks
>perl

use strict;
use warnings;

# same as $RE{net}{IPv4} dotted decimal
my $octet   = qr{ 25 [0-5] | 2 [0-4] \d | [01]? \d \d? }xms;
my $rx_ipv4 = qr{ (?> $octet (?: [.] $octet){3}) }xms;

my $ip = 'csteppfw pts/0        2022-06-27 15:53 (192.168.5.100)';

($ip) = $ip =~ m{ (?<! \d) $rx_ipv4 (?! \d) }xmsg;
print "'$ip' \n";

^Z
'192.168.5.100'