You have the matcing correct, but you did not save any of the data you matched. You may want to take a look at the perlre man page, in praticular what parenthesis are for. Something like the follwing (untested) code :

while (<DATA>) {

    if ($_ =~ /^(\d+\s+\[\d+\.\d+\.\d+\.\d+\]\s+[\d+\.\d+\.\d+\.\d+\])
+/) {
        print "Match=$1\n";
    }
}
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The addition of getting the field is an excersize left to the reader.

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