Install the service using our loved yum.
- yum install net-snmp net-snmp-utils
To the configuration; which can be found here : /etc/snmp/snmpd.conf
I however remove the original one -most of the time- and just copy/paste the one I use on all servers; Keep the original for reference, although its very verbose (IMHO)
- mv /etc/snmp/snmpd.conf /etc/snmp/snmpd.conf.ori
This is the config I use and why in the comments :
# this create a SNMPv1/SNMPv2c community named "my_servers" # and restricts access to LAN adresses 192.168.0.0/16 (last two 0's are ranges) rocommunity my_servers 192.168.0.0/16 # setup info syslocation "rack 1, room 3, Antwerpen serverrroom" syscontact "Svenn" # open up agentAddress udp:161 # run as agentuser root # dont log connection from UDP: dontLogTCPWrappersConnects yes # fix for larger then 2TB disks (raid!) realStorageUnits 0
Before we can start the service, I like to have SNMP a little less verbose, since by default EVERY connection is logged in rsyslog. Considering I poll every 5 minutes, this adds up in /var/log/messages. So lets down it a bit, this can be done in /etc/sysconfig/snmpd add the following, to reduce the verbosity :
The correct way to do this is to add a profile for SNMP to firewalld. Using UDP 161 not TCP vim /etc/firewalld/services/snmp.xml <?xml version="1.0" encoding="utf-8"?> <service> <short>SNMP</short> <description>SNMP protocol</description> <port protocol="udp" port="161"/> </service> Then you should reload your firewall firewall-cmd --reload Then you need to add the service to your public zone firewall-cmd --zone=public --add-service snmp --permanent Then finally reload your firewall again firewall-cmd --reload
When this has been done, lets open up the Iptables to allow for requests. (change the -s if you have another range!)
- iptables -A INPUT -s 192.168.0.0/16 -p udp –dport 161 -j ACCEPT
Starting the daemon
- systemctl start snmpd
- systemctl enable snmpd
- extend nfs-server /etc/snmp/nfs-server.sh
- extend zfs /etc/snmp/zfs-linux
- extend ups-apcups /etc/snmp/ups-apcups.sh
For more info on these, I would refer to the documentation of LibreNMS.
Multiple extends available !
Testing … 123
On the machine you are installing LibreNMS or any other NMS package try :
- snmpwalk -c my_servers -v1 servername SNMPv2-MIB::sysDescr.0
This should return the system description. (only change -c COMMUNITY and -v1 SERVERNAME/IP)