====== CentOS6 ======
<pre>
yum -y install net-snmp net-snmp-utils
mv /etc/snmp/snmpd.conf /etc/snmp/snmpd.conf.orig
</pre>

<pre>
# nano /etc/snmp/snmpd.conf
rocommunity  public
syslocation  "fs1"
syscontact  mail@mail.ru
</pre>

<pre>
service snmpd restart
chkconfig snmpd on
</pre>

* iptables
<pre>
# nano /etc/sysconfig/iptables

-A INPUT -m state --state NEW -m tcp -p tcp --dport 161 -j ACCEPT
-A INPUT -m state --state NEW -m udp -p udp --dport 161 -j ACCEPT
</pre>