For example, I will configure SNMP on Juniper MX204.
Let’s go to the configuration mode:
configure
Let’s move on to configuring snmp:
edit snmp
Let’s specify the community (instead of IXNFO.COM) and the IP address of the snmp client (in my case, the Zabbix server):
set community IXNFO.COM clients 192.168.5.5/32 authorization read-only
You can also execute the command from the main configuration mode:
set snmp community IXNFO.COM clients 192.168.5.5/32 authorization read-only
If there are many SNMP client IP addresses, then create a list and indicate it when adding community:
set client-list list0 192.168.3.0/24
set client-list list0 192.168.5.5/32
set community IXNFO.COM client-list-name list0 authorization read-only
If necessary, we will indicate the rest of the data to the device:
set name "ixnfo.com"
set description "TEST"
set location "TEST"
set contact "admin@ixnfo.com"
Let’s check the added SNMP configuration:
show
Let’s check the configuration and apply:
commit check
commit
After that SNMP v2 should work.
You can delete the entered command or community like this:
delete community IXNFO.COM
delete community IXNFO.COM clients 192.168.5.5/32
Or just restore the previous configuration:
rollback ?
rollback 0
Let’s exit the snmp hierarchy and check the snmp configuration again:
exit
show snmp
show | match snmp | display set
Here is an example of log entries when someone connects with the wrong community or from an unresolved IP address:
show log messages | last 10
SNMPD_AUTH_FAILURE: nsa_log_community: unauthorized SNMP community from x.x.x.x to x.x.x.x (public)
SNMPD_AUTH_RESTRICTED_ADDRESS: nsa_initial_callback: request from address x.x.x.x not allowed
To diagnose problems with SNMP, you can write more detailed logs to a separate file, I will give an example configuration:
set snmp traceoptions file SNMP size 1m
set snmp traceoptions flag general
set snmp traceoptions lag varbind-error
juniper.net/documentation/us/en/software/junos/network-mgmt/topics/ref/statement/traceoptions-edit-snmp.html
See also my articles:
SNMP OID for Juniper
SNMP OID and MIB for interfaces