installing moodle 2.3.4+ on webserver XAMPP 1.8.1 (o.s. ubuntu 12.04)

I'm trying toinstallmoddleusing XAMPP2.3.4+1.8.1aswebserver (o.s. Ubuntu12.04), the firsterror messageis:"ZipPHP extensionsmust be installedandactivated."

Ithink I understoodthat it lacks theextensionzip.so.I've tried looking for in theextensions directory/opt/lampp/lib/php/extensions/no-debug-non-zts-20100525, but the file zip.sois not present andthereforeif I removethe comment on thelineextension =zip.so in the file php.inienter theXAMPPwebservercrash.

How can Ido?

thanks, greetings

MassimoRomagnoli