The program is able to listen for syslog messages via UDP or TCP and can listen for version 1 or 2c SNMP traps.
By default, listening on UDP port 514 is enabled. This the most common method of syslog delivery.
Some firewalls (Cisco PIX) and other syslog daemons are able to send syslog messages via TCP. The Cisco PIX uses TCP port 1468 to send messages on. Listening on TCP is not enabled by default.
The reception and decoding of version 1 and 2c SNMP traps is supported, but not enabled by default. The normal SNMP trap listening port is UDP 162.
There are three separate listening sockets. UDP, TCP and SNMP.
Additionally, a keep alive message can be injected into the input stream to simulate traffic.