http://net-snmp.sourceforge.net/
http://www.lint.ne.jp/~tomo/server/snmp/rh80-snmpd.html
http://ykondou.dyndns.org:8080/nms/mrtg.shtml
http://www.cysol.co.jp/project/IPv6/index_j.html
https://www.netsecurity.ne.jp/article/2/6784.html
http://acorn.zive.net/~oyaji/mrtg/snmp_linux.htm