User Manual

Additional Remote Networking Basic Security
5-2
3 Enable authentication on each port that will be used for incoming logins.
Figure 5-2: Enabling Port Authentication
5.1.2 Filter Lists
Filters enable the SCS to restrict packet traffic. Each filter specifies a particular rule, for example, only IP
packets are permitted passage. Packets that pass the filter are forwarded; all others are discarded.
Filters are organized into ordered filter lists, referenced by name. For example, a filter named firewall may
permit forwarding of packets that match a particular IP rule, but deny passage to packets that match a
generic rule.
Filter lists are associated with sites. Table 5-1 describes the available filter lists and how they are used.
When a site with an associated filter list receives a packet, the SCS compares the packet against each filter
starting with the first filter on the list. If the packet matches any of the filters, the packet is forwarded or
discarded according to the filter’s specification. If the packet does not match any of the filters in the list, that
packet is not forwarded.
The order filters appear in a list is very important. For example, consider the following filter list.
1 Allow any packet
2 Deny all IP traffic matching a particular rule
When this filter list is associated with a site, all packets are forwarded. Packets are compared to filters in
the order in which the filters appear in the list. Because all packets match the specification of “any packets,”
all packets are forwarded without being compared to the second filter.
Switching the order of the filters has a significant effect. Examine the filter list below, where the order of
the above two filters is reversed.
Local>> DEFINE PORT 2 AUTHENTICATE ENABLED
Table 5-1: Types of Filter Lists
Type of Filter List Purpose
Idle Determines whether the site will remain active. Packets that
pass the filter will reset the site’s idle timer, preventing the
site from being timed out.
Incoming Determines whether to forward incoming packets received
from a remote site. Packets that pass the filter will be
forwarded.
Outgoing Determines whether to forward outgoing packets to a
remote site. Packets that pass the filter will be forwarded.
Startup Determines whether a site will initiate a connection to a
remote site. When a packet passes the filter, the SCS will
initiate an outgoing connection. (If an outgoing connection
currently exists, this filter will be ignored.)