智象运维 | 如何利用snmp trap监控交换机端口状态（Up/Down）
原理：在智象智能运维平台系统配置安装过程中，利用snmp协议在交换机上设置trap陷阱，
当端口状态发生改变时，通知监控主机，监控主机配置snmptrapd进行接收，然后告警给用户。
参考文献：http://www.net-snmp.org/wiki/index.php/TUT:Configuring_snmptrapd
一、智象运维中交换机配置部分（需要查看具体产品文档，这里以华为S9306为例）：
display snmp-agent trap feature-name ifnet all
------------------------------------------------------------------------------
Feature name: IFNET
Trap number : 17
------------------------------------------------------------------------------
Trap name Default switch status Current switch status
hwIfFlowDown off off
hwIfFlowUp off off
hwIfNameChange off off
hwIfNameChangeResume off off
hwIfMonitorInputRateRising off off
hwIfMonitorInputRateResume off off
hwIfMonitorOutputRateRising off off
hwIfMonitorOutputRateResume off off
hwEntityExtCfmOverSlot off off
hwEntityExtCfmOverCard off off
linkDown off off
linkUp off off
hwIfControlFlapSuppress off off
hwIfControlFlapResume off off
hwExtInterfaceDelete off off
hwIfMonitorCrcErrorRising off off
hwIfMonitorCrcErrorResume off off
------------------------------------------------------------------------------
snmp-agent trap enable feature-name ifnet trap-name linkdown
snmp-agent trap enable feature-name ifnet trap-name linkup
snmp-agent target-host trap address udp-domain 192.168.1.172 source Vlanif 4001 params securityname public v2c
dis snmp-agent target-host
Target-host NO. 1
-----------------------------------------------------------
IP-address : 192.168.1.172（trap服务器地址）
Source interface : Vlanif4001
VPN instance : -
Security name : %@%@Wkz7H#,G'@JZvn-ayZ"Nf2')%@%@
Port : 162
Type : trap
Version : v2c
Level : No authentication and privacy
NMS type : NMS
With ext-vb : No
-----------------------------------------------------------
二、trap服务器配置：
1、安装snmptrapd，根据系统类型安装并配置：
Ubuntu:
apt-get install snmptrapd -y
CentOS:
yum install -y net-snmp net-snmp-utils net-snmp-perl
2、配置snmpd：
cat /etc/snmp/snmptrapd.conf
# Example configuration file for snmptrapd
#
# No traps are handled by default, you must edit this file!
#
# authCommunity log,execute,net public
# traphandle SNMPv2-MIB::coldStart /usr/bin/bin/my_great_script cold
authCommunity log,execute,net public
traphandle IF-MIB::linkDown /monitor/notification.sh
traphandle IF-MIB::linkUp /monitor/notification.sh
三、编写脚本：
1、告警脚本：
[root@monitor monitor]# cat notification.sh
#!/bin/sh
read blank
read ip
switch_ip=`/bin/echo $ip | /bin/awk -F '[' '{print $2}' | /bin/awk -F ']' '{print $1}'`
while read oid val
do
if [ "$oid" = "SNMPv2-MIB::snmpTrapOID.0" ];then
if_status=`/bin/echo $val | /bin/awk -F"link" '{print $2}'`
fi
if /bin/echo $oid | /bin/grep ifDescr;then
if_name=`/bin/echo $val`
fi
done
if [ $if_status = "Up" ];then
msg=`/bin/echo "OK! Switch($switch_ip) -- $if_name -- $if_status"`
else
msg=`/bin/echo "Critical! Switch($switch_ip) -- $if_name -- $if_status"`
fi
/monitor/sendwx.sh "$msg"
2、编写sendwx.sh告警通知脚本，根据实际情况自行编写，这里暂不作示例。
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