After some googling around I found that I need to install Net-SNMP on

?? those are two different modules

SNMP requires a c-library, netsnmp.lib , which won't be found on cpan, and like the README says, you get it from http://www.net-snmp.org/

Net::SNMP doesn't need ppm, you can install it with  perl -MCPAN -e "install Net::SNMP"