If you notice this error on your Ubuntu:
PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php5/20100525/snmp.so' - /usr/lib/php5/20100525/snmp.so: cannot open shared object file: No such file or directory in Unknown on line 0
You can fix it by installing a another, missing php5 package:
user# sudo apt-get install php5-snmp
PHP Startup: Unable to load dynamic library ‘/usr/lib/php5/20100525/snmp.so’