you can try this:

{
    local $/ = undef;
    open(FILE, "<file.txt") or die "open failed on file.txt: $!";
    $wholetext = <FILE>;
    close(FILE);
}
if ( $wholetext =~ /CONNAME\((\d+?\.\d+?\.\d+?\.\d+?)\)\s+CURRENT/ ) 
{
     print $1;
}

__DATA__

    CONNAME(163.231.99.129)                 CURRENT
    CHLTYPE(SVRCONN)                        STATUS(RUNNING)
    LSTMSGTI(03.45.47)                      LSTMSGDA(2003-11-21)

__OUTPUT__

163.231.99.129
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