$user_param{source_addr} ||= '.'; # default value for param
$user_param{dest_addr} ||= '.';

while (<DATA>) {
    my @data = split(/\s/, $_);
    next unless $data[2] =~ $user_param{source_addr};        
    next unless $data[3] =~ $user_param{dest_addr};
    # ...

    print $_;
}