Description

This article gives the reason for the "SNMPD_AUTH_FAILURE" log message to be seen on MX Series routers and recommends the ideal configuration to prevent this log message.

 

Symptoms

Simple Network Management Protocol (SNMP) has been configured and the following log message is seen on the device: 

"SNMPD_AUTH_FAILURE: agent_io_reader: failed input interface authorization from 10.x.x.x to 10.x.x.x"

Solution

Check whether SNMP requests are restricted to the interface list. If the requests come from a non-listed interface, the above log message is expected. 

snmp {
     location XXXX;
     contact "[email protected]";
     community Test {
         authorization read-only;
         clients {
             10.10.10.10/32;

 

Specify the names of any logical or physical interfaces that should have SNMP access privileges. Any SNMP requests that enter the router or switch from interfaces that are not listed are discarded.

If you identify that SNMP server is reachable via any interface, include that interface in SNMP: 

lab@MX> show route 10.10.10.10

inet.0: 814509 destinations, 4668764 routes (805294 active, 2 holddown, 2728493 hidden)
+ = Active Route, - = Last Active, * = Both

10.10.10.10/32      *[OSPF/150] 2w1d 02:05:09, metric 116, tag 0
                     to 10.1.1.2 via xe-0/0/4.0
                   > to 10.1.1.6 via xe-0/0/6.0
                     to 10.1.1.10 via xe-0/1/4.0
                     to 10.1.1.14 via xe-0/1/6.0

>configure
#set snmp interface xe-0/0/6.0
#commit

If you see SNMP requests from ​non-authorized IPs, configure a firewall filter to discard packets from the source that you do not want to authorize.