SNMP Hands - On ¶

Goals ¶

• Install and learn to use the SNMP commands
• Install vendor specific MIBs and use those with the SNMP commands

Notes ¶

• For below hands-on we will be using Ubuntu 20.04 version.
• If you are installing snmp client (manager) tools on a remote server/computer you will need to connect the server through a SSH connection.

Installing SNMP Client (Manager) tools ¶

Connect to the server which will be used as the NMS (Network Management Station) and Open the Terminal program.

Update your software package repository

$ sudo apt-get update

This might take a few moments if everyone in class is doing this at the same moment.

Install the net-snmp tools:

$ sudo apt-get install snmp
$ sudo apt-get install snmp-mibs-downloader

The second of the two commands downloads the standard IETF and IANA SNMP MIBs which are not included by default.

Now, edit the file /etc/snmp/snmp.conf:

$ sudo vi /etc/snmp/snmp.conf

Note: Here we are using vi editor. You can use any text editor you are familiar with

Change this line:

mibs :

so that it looks like:

# mibs :

(You are "commenting out" the empty mibs statement, which was telling the snmp* tools not to automatically load the mibs in the /usr/share/mibs/ directory)

User specific SNMP configurations ¶

Now, in your home directory make a .snmp directory with file snmp.conf inside it, make it readable only be you, and add the credentials to it:

$ cd
$ mkdir .snmp
$ chmod 700 .snmp/
$ vi .snmp/snmp.conf

Put the following contents in the file:

defVersion 3

# SNMP v3 Configurations
defSecurityLevel authNoPriv
defSecurityName admin
defAuthPassphrase <class passowrd>
defAuthType SHA

# SNMP v2c default community string
defCommunity <class passowrd>

Configuration of SNMP Agent on Routers and Switches ¶

Cisco ¶

connect to your router and go to configure mode.

Router> enable

Router# configure terminal

Now we need to add an Access Control List rule for SNMP access, turn on SNMP, assign a read-only SNMP community string as well as a SNMPv3 group and user and tell the router to maintain SNMP information across reboots. To do this we do:

Router(config)# access-list 99 permit 192.248.6.0 255.255.255.0
Router(config)# snmp-server community <class passowrd> ro 99
Router(config)# snmp-server group ReadGroup v3 auth access 99
Router(config)# snmp-server user admin ReadGroup v3 auth sha <Class Password>
Router(config)# snmp-server ifindex persist
Now let's exit and save this new configuration to the routers permanent config.

Router(config)# exit
Router# write memory            
Router# exit       

HP ¶

Connect to the Router and go to config mode

<Router> system-view

Add the following configurations

[Router]acl number 2000
[Router-acl-basic-2000]rule 0 permit source 192.248.6.0 0.0.0.255
[Router]snmp-agent
[Router]snmp-agent community read <class passowrd>
[Router]snmp-agent sys-info version all
[Router]snmp-agent group v3 ReadGroup authentication acl 2000
[Router]snmp-agent usm-user v3 admin ReadGroup authentication-mode sha <class passowrd>

Testing SNMP ¶

Now we have both a SNMP Manager and SNMP Agent. To check that your SNMP installation works, run the snmpstatus command on the SNMP Manager host.

$ snmpstatus <IP_ADDRESS> 

Note that you just used was the SNMPv3 because we set the default version as SNMPv3. Try again, adding "-v2c" as a parameter. Notice that the command automatically uses the community string in the snmp.conf file instead of the v3 user credentials. Try "-v1".

To use the SNMP v2 or v1 we can add an option as below. Which will override the settings in the configuration file(/.snmp/snmp.conf).

snmpstatus -v2c <IP_ADDRESS> snmpstatus -v1 <IP_ADDRESS>

Again we didn't want set Community string as it was set in the manager configuration file.

For the Router,

#snmpstatus <Router IP>

For the Switch,

#snmpstatus <Switch IP>