====== CentOS 7 SNMP 設定 ======

  * 安裝環境 : CentOS Linux release 7.5.1804 (Core)
  * getenforce : Disabled
  * firewall-cmd --list-services : http https ssh **snmp**

===== 安裝套件 =====
<code sh>
yum -y install net-snmp net-snmp-utils
</code>

===== 設定 snmp 的定義 =====
  * 設定 192.168.1. 的網段可以透過 community nms01 讀取
  * 設定 192.168.0. 的網段可以透過 community nms02 讀取
<code sh>vi /etc/snmp/snmpd.conf</code><file>
com2sec notConfigUser  default       public
com2sec local localhost public
com2sec mynetwork 192.168.1.0/24 nsm01
com2sec mytpnetwork 192.168.0.0/24 nms02

group MyRWGroup v1 local
group MyRWGroup v2c local
group MyROGroup v1 mynetwork
group MyROGroup v2c mynetwork
group MyROGroup v1 mytpnetwork
group MyROGroup v2c mytpnetwork

view    systemview    included   .1.3.6.1.2.1.1
view    systemview    included   .1.3.6.1.2.1.25.1.1

access  notConfigGroup ""      any       noauth    exact  systemview none none

view all    included  .1                               80

access MyROGroup "" any noauth prefix all none none
access MyRWGroup "" any noauth prefix all all all

syslocation New Taipei City, Taiwan
syscontact InfoTech <infotech@ichiayi.com>

dontLogTCPWrappersConnects yes

proc snmpd

disk / 10%
</file><code sh>
systemctl restart snmpd.service
systemctl enable snmpd.service
</code>

===== 驗證與測試 =====
  * 主機端確認 snmp 服務有啟動<code sh>
systemctl status snmpd.service
netstat -auntp | grep snmp
</code>
  * 在網管端 Exp. 192.168.1.200 使用 snmpwalk -c nms01 進行檢測<code sh>
snmpwalk -c public -v 2c 192.168.0.233
</code>

<note>
  * snmpwalk 結果出現 <code>
No Response from xxx.xxx.xxx.xxx</code>
  * server log 出現類似 <code>
snmpd[942]: Connection from UDP: [192.168.xxx.xxx]:45239->[192.168.xxx.xxx]:161 REFUSED</code>

  * 可能就需要在 /etc/hosts.allow 裡面加入 snmp client 端的 IP Exp.192.168.1.240<code h /etc/hosts.allow>
#
# hosts.allow   This file contains access rules which are used to
#               allow or deny connections to network services that
#               either use the tcp_wrappers library or that have been
#               started through a tcp_wrappers-enabled xinetd.
#
#               See 'man 5 hosts_options' and 'man 5 hosts_access'
#               for information on rule syntax.
#               See 'man tcpd' for information on tcp_wrappers
#
sshd:ALL
snmpd: 192.168.1.240
</code>
</note>

===== 參考網址 =====
  * http://blog.jangmt.com/2015/09/centos-7-snmpd-centos-7-snmp-install.html
  * https://www.liquidweb.com/kb/how-to-install-and-configure-snmp-on-centos/
  * http://blog.secaserver.com/2012/08/snmpd-connection-udp-refused/


{{tag>NMS snmp}}