Ubuntu Server 12.04

root@gorbachev# apt-get install libsnmp-dev snmpd snmp g++ make ncurses-dev
root@gorbachev# tar -zxf asterisk-1.4.43.tar.gz
root@gorbachev# cd asterisk-1.4.43/
root@gorbachev# ./configure
root@gorbachev# make menuselect

Resource Modules; res_snmp[*]

root@gorbachev# make
root@gorbachev# make install
root@gorbachev# make samples

/etc/asterisk/res_snmp.conf

edit lines:

subagent = yes 
enabled = yes

/etc/snmp/snmpd.conf

edit lines: 
createUser asteriskUser MD5 "<your password>" DES
rwuser asteriskUser priv
master agentx
agentXSocket	/var/agentx/master
agentXPerms 0660 0550 nobody asterisk

root@gorbachev# /etc/init.d/snmpd stop
root@gorbachev# net-snmp-config --create-snmpv3-user -ro -a MD5 -A AuthMobilon -x AES -X PrivacyMobilon asterisk
root@gorbachev# /etc/init.d/snmpd start
root@gorbachev# asterisk
root@gorbachev# snmpwalk -v 3 -u asterisk -l authPriv -a MD5 -A AuthMobilon -x AES -X PrivacyMobilon 127.0.0.1 iso.3.6.1.4.1.22736.1.1.1

Block UDP 161,162 port on firewall.