It will be much easier for people to help you with your problem if you posted more information, for example the output you get when trying to install the module. You can put <readmore> tags around such text, that way it won't be seen in Newest Nodes or other lists.
About the only helpful thing I can say with the information you have given so far is are you sure you have Ubuntu libdumbnet-dev package installed? That contains the libraries you'll need when compiling Net::Libdnet. Also, Net::Libdnet is rather ancient, and automatic CPAN tests show it fails to install on about half of all modern Linux variants, so maybe the module is broken (or broken for recent versions of Libdnet).
Are you posting in the right place? Check out Where do I post X? to know for sure.
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
Want more info? How to link
or How to display code and escape characters
are good places to start.