public List<IPAddress> getEnforceHosts() throws GuacamoleException {
        return environment.getProperty(TOTP_ENFORCE_HOSTS, Collections.emptyList());
    }
Return the list of IP addresses and/or subnets for which MFA authentication via the TOTP
module should be explicitly enabled, requiring users logging in from hosts specified in
the list to complete MFA.

@return
    A list of IP addresses and/or subnets for which MFA authentication
    should be explicitly enabled.

@throws GuacamoleException 
    If guacamole.properties cannot be parsed, or an invalid IP address
    or subnet is specified.
extensions/guacamole-auth-totp/src/main/java/org/apache/guacamole/auth/totp/conf/ConfigurationService.java