Here are the instructions I followed to get SNMP and Cacti working on Gentoo:
emerge cacti cacti-cactid
groupadd cacti
useradd -g cacti -G cron cactiuser
cd /var/www/localhost/htdocs/cacti/
mysql –user=root cacti < cacti.sql
chown -R cactiuser rra/ log/
mysql
mysql> create database cactidb;
mysql> grant all on cactidb.* to root;
mysql> grant all on cactidb.* to root@localhost;
mysql> grant all on cactidb.* to cactiuser;
mysql> grant all on cactidb.* to cactiuser@localhost;
mysql> set password for cactiuser@localhost=password(‘mycactipw’);
mysql> exit
nano config.php
$database_type = "mysql";
$database_default = "cacti";
$database_hostname = "localhost";
$database_username = "cactiuser";
$database_password = "mycactipw";
Now open browser to http://localhost/cacti
Follow the steps:
Login as admin password admin
change password
Back to the command line
crontab -e -u cactiuser
*/5 * * * * /usr/bin/php /var/www/localhost/htdocs/cacti/poller.php > /dev/null 2>&1
nano -w /etc/snmp/snmpd.conf
com2sec local 127.0.0.1/32 public
com2sec local 10.10.10.0/24 publicgroup MyROGroup v1 local
group MyROGroup v2c local
group MyROGroup usm localview all included .1 80
access MyROGroup "" any noauth exact all none none
syslocation MyLocation
syscontact Me <me@somewhere.org>
/etc/init.d/snmpd start
rc-update add snmpd default
Should be all good!