Monitoring the Router
Once the access configuration is in place, you should monitor the router for health and analysis. The two primary methods of remote monitoring are via SNMP and syslog (system logging). SNMP is a way to gather statistics and other event information off the router, whereas syslog is used to gather various log messages off the router. To validate these types of messages, you should use proper time and date stamping, which is often implemented by using NTP.
Syslog was originally developed as a method to send information for the sendmail application in BSD, but it was so useful that it was extended to other applications and operating systems. Essentially, syslog is a standard way to send log messages across an IP network.
Syslog describes the actual transport mechanism used to send these messages and is often used to describe the actual application that is sending them. Originally, it was an “industry” standard and was not attached to an informational RFC until 2001, with RFC 3164, “The BSD Syslog Protocol.”
Syslog messages are sent over UDP with a destination port of 514. The IP transport mechanism is defined and not the actual syslog content. It is left to the discretion of the application or system coder to create an informative message to the receiver. The message always contains a message severity level and a facility level. The facility level can be defined as the type of message that is being sent, and the severity level indicates the message’s importance. ...