Here is a sample of my config file for snort.debian.conf
DEBIAN_SNORT_STARTUP="boot"
DEBIAN_SNORT_HOME_NET="[Use commas between multiple addresses]"
DEBIAN_SNORT_OPTIONS="-A fast -I -N --nolock-pidfile"
DEBIAN_SNORT_INTERFACE="eth1"
DEBIAN_SNORT_SEND_STATS="true"
DEBIAN_SNORT_STATS_RCPT="root"
DEBIAN_SNORT_STATS_THRESHOLD="1"
This is for the eth1 interface (the interface with no IP address)
Snort is left unconfigured for the management interface. This is done by using the following syntax:
DEBIAN_SNORT_STARTUP="manual"
In the snort.conf file I have configured the HOME_NET variables as well (just to be sure) and the EXTERNAL_NET as well.
In debian I know that the snort.debian.conf file is used for configuration of variables. The question would be then what file SUPERCEEDS the other. That I do know. I would advise you to log in through SSH to Solarwinds, go to Appliance and enter "checklogs". From here you can check both the daemon logs(5) or Snort(3...i think). The daemon logs will let you know if you have a snort configuration issue. The Snort log will show you alerts.
Hope this helps Good luck!