Which ports need to be opened in order to receive rulebase updates?

A server should be able to make outbound connections without inspection to port 25 -- this is typical for mail servers since port 25 is for SMTP. SNF uses this also for SYNC which does not look like SMTP, so some newer firewalls that inspect traffic may break these connections. Firewalls must be told NOT to inspect this traffic from your mail server.


When SNF sees that a new rulebase is available during its SYNC session, the rulebase file itself will be downloaded using an ordinary HTTP connection - so you also need to allow outbound connections to port 80.