SmtpMonitor The SMTP monitor tests for SMTP service availability on a node. The monitor first tries to establish a TCP connection on the specified port. If a connection is established, a service banner should have been received. The monitor makes sure the service banner is a valid SMTP banner (starts with "220"). If the banner is valid, the monitor sends a HELO SMTP command, identifying itself with the hostname of the OpenNMS server, and makes sure the service answers with a valid response (starts with "250"). If the response to the HELO is valid, the monitor issues a QUIT SMTP command. The service is considered available if the service’s answer to the HELO command is valid (starts with "221"). The behaviour can be simulated with telnet or netcat: $ nc -v gmail-smtp-in.l.google.com 25 Ncat: Version 7.60 ( https://nmap.org/ncat ) Ncat: Connected to 2607:f8b0:4002:c06::1a:25. 220 mx.google.com ESMTP j17-v6si13545102ywb.87 - gsmtp HELO opennms.com 250 mx.google.com at your service QUIT 221 2.0.0 closing connection j17-v6si13545102ywb.87 - gsmtp Monitor Facts Class Name org.opennms.netmgt.poller.monitors.SmtpMonitor Remote Enabled true Configuration and Use Table 1. Monitor specific parameters for the SmtpMonitor Parameter Description Required Default value port TCP port to connect to. optional 25 retry Number of attempts to find the service available. optional 0 timeout Timeout in milliseconds for the underlying socket’s connect and read operations. optional 3000 Examples <service name="SMTP" interval="300000" user-defined="false" status="on"> <parameter key="retry" value="1" /> <parameter key="timeout" value="3000" /> <parameter key="port" value="25" /> <parameter key="rrd-repository" value="${install.share.dir}/rrd/response" /> <parameter key="rrd-base-name" value="smtp" /> <parameter key="ds-name" value="smtp" /> </service> <monitor service="SMTP" class-name="org.opennms.netmgt.poller.monitors.SmtpMonitor" /> SmbMonitor SnmpMonitor