If you have a duplicate "allow" statements defined in a config file, for example:
set daemon 30 # check services at 30 seconds intervals set logfile syslog set httpd port 2812 and use address localhost # only accept connection from localhost allow localhost # allow localhost to connect to the server and allow localhost # duplicate entry allow admin:monit # require user 'admin' with password 'monit' set daemon 60 include /etc/monit.d/*
Startup will fail saying that the "localhost" entry is incorrect:
Starting monit: /etc/monit.conf:7: Erroneous network or host identifier localhost 'localhost'
Same situation happens when specifying a network. The issue is that either the function Engine_addHostAllow (for hostnames) or Engine_addNetAllow (for networks), both defined in src/http/engine.c, returns false if they don't add the entry, even if it's already there, which will trigger the error message above and startup to fail.