Running tcpdump, Wireshark or sniffer network packet capture shows authentication requests set from the agent on 5500 UDP, but there are no replies coming back out of the Authentication Manager server.
See article 000016395 - Using tcpdump to troubleshoot authentication issues with RSA Authentication Manager 8.x for instructions using the tcp dump command.
Following the steps in the article, run the command ./tcpdump -i eth0 -s 1514 -Z root port 5500.
In addition, proof of a silent discards will be seen in the /opt/rsa/am/server/logs/imsTrace.log
If logging is set to verbose, (see 000018205 - How to turn on/off verbose offline authentication logging), the source IP address of the unknown agent will be listed as an error. For example,
2014-03-07 09:55:21,121, [[ACTIVE] ExecuteThread: '0' for queue: 'weblogic.kernel.Default (self-tuning)'], (AgentAccessSQL.java:130),
trace.com.rsa.authmgr.internal.admin.common.dal.sql.DataObjectAccessSql,
ERROR, PACEC81.credito.bcp.com.pe,,,,Unable to lookup class
com.rsa.authmgr.internal.admin.agentmgt.dal.Agentwith ip address: 192.168.1.5