报错信息：
[root@localhost backup]# yum -y install net-snmp
Loaded plugins: fastestmirror
Repository base is listed more than once in the configuration
Repository addons is listed more than once in the configuration
Repository extras is listed more than once in the configuration
Repository centosplus is listed more than once in the configuration
Repository contrib is listed more than once in the configuration
Loading mirror speeds from cached hostfile
* updates: centos.ustc.edu.cn
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package net-snmp.x86_64 1:5.3.2.2-9.el5_5.1 set to be updated
--> Processing Dependency: net-snmp-libs = 1:5.3.2.2-9.el5_5.1 for package: net-snmp
--> Processing Dependency: libsensors.so.3()(64bit) for package: net-snmp
--> Running transaction check
---> Package lm_sensors.x86_64 0:2.10.7-9.el5 set to be updated
---> Package net-snmp-libs.i386 1:5.3.2.2-9.el5_5.1 set to be updated
---> Package net-snmp-libs.x86_64 1:5.3.2.2-9.el5_5.1 set to be updated
--> Finished Dependency Resolution
Dependencies Resolved
===================================================================================================================================================
Package Arch Version Repository Size
===================================================================================================================================================
Installing:
net-snmp x86_64 1:5.3.2.2-9.el5_5.1 update 702 k
Installing for dependencies:
lm_sensors x86_64 2.10.7-9.el5 base 525 k
Updating for dependencies:
net-snmp-libs i386 1:5.3.2.2-9.el5_5.1 update 1.3 M
net-snmp-libs x86_64 1:5.3.2.2-9.el5_5.1 update 1.3 M
Transaction Summary
===================================================================================================================================================
Install 2 Package(s)
Upgrade 2 Package(s)
Total size: 3.7 M
Downloading Packages:
warning: rpmts_HdrFromFdno: Header V3 DSA signature: NOKEY, key ID e8562897
update/gpgkey | 1.8 kB 00:00
Public key for net-snmp-libs-5.3.2.2-9.el5_5.1.x86_64.rpm is not installed
在网上解决方法：
此时要导入rpm的签名信息即可
以root登录，执行下面命令
# rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release
Linux版本是CentOS 7.4
执行下面命令
#rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7