A slightly different approach so as to replace each digit of the masked octets with an 'x' rather than the whole octet with a single 'X' just as an exercise.

$ perl -Mstrict -Mwarnings -E '
open my $inFH, q{<}, \ <<EOD or die $!;
10.128.99.190 10.128.100.100
1.1.1.1 2.2.2.2
3.3.3.3 4.4.4.4
100.100.100.100 200.200.200.200
EOD

print for
   map {
       s{ (\d+\.\d+) (?= (?:\.\d+){2} ) }
        { do{ my $c = $1; $c =~ tr{0-9}{x}; $c } }xeg;
       $_;
       } <$inFH>;'
xx.xxx.99.190 xx.xxx.100.100
x.x.1.1 x.x.2.2
x.x.3.3 x.x.4.4
xxx.xxx.100.100 xxx.xxx.200.200
$

[download]

I hope this is of interest.

Cheers,

JohnGG

In reply to Re: Patternmatching IPaddresses by johngg
in thread Patternmatching IPaddresses by vyeddula

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.