Safe A useful network service can also prove useful to attackers. But the agents used by network devices such as routers, switches, and terminal servers to report hundreds of statistics relevant to the proper running of a network device can also give up lots of useful information to attackers. The requests and replies refer to variables accessible to the agent software.
Management software can also send requests to set values for certain variables.
And finally, agents can respond on their own by sending a trap message. Where SNMP is complex is in the definition of the variables. A dot represents the root of the tree of objects, and numbers represent the remainder of the nodes in the tree. For example, to query the TCP connection table, you would begin with the object identifier .1.3.6.1.2.1.6.13, which is not a very human-friendly name, but it does work well for the agents. Like many other Internet protocols, security was not designed into the first two versions of the protocol.