features as IDP.
•
The Service can be specified as all_services which includes all possible protocols.
Creating a Drop All Rule
Traffic that does not match any rule in the IP rule set is, by default, dropped by NetDefendOS. In
order to be able to log the dropped connections, it is recommended that an explicit IP rule with an
action of Drop for all source/destination networks/interfaces is placed as the last IP rule in the IP
rule set. This is often referred to as a Drop All rule.
Tip: Include the rule set name in the drop all name
There may be several IP rule sets in use. It is recommended to include the IP rule set
name in the name of the drop all rule so it can be easily identified in log messages.
For example, the drop all rule for the main rule set should be called main_drop_all or
similar.
The IP Addresses in IP Rules can be IPv4 or IPv6
IP rules support either IPv4 or IPv6 addresses as the source and destination network for a rule's
filtering properties.
However both the source and destination network must be either IPv4 or IPv6. It is not permissible
to combine IPv4 and IPv6 addresses in a single rule. For this reason, two Drop All rules will be
required when using IPv6, one for IPv4 and one for IPv6 as shown below:
Name
Action
Source Iface
Source Net
Dest Iface
Dest Net
Service
DropAll
Drop
any
all-nets
any
all-nets
all_services
DropAll6
Drop
any
all-nets6
any
all-nets6
all_services
For further discussion of this topic, see Section 3.2, “IPv6 Support”.
Traffic Flow Needs an IP Rule and a Route
As stated above, when NetDefendOS is started for the first time, the default IP rules drop all traffic
so at least one IP rule must be added to allow traffic to flow. In fact, two NetDefendOS components
need to be present:
•
A route must exist in a NetDefendOS routing table which specifies on which interface packets
should leave in order to reach their destination.
A second route must also exist that indicates the source of the traffic is found on the interface
where the packets enter.
•
An IP rule in a NetDefendOS IP rule set which specifies the security policy that allows the
packets from the source interface and network bound for the destination network to leave the
NetDefend Firewall on the interface decided by the route.
If the IP rule used is an Allow rule then this is bi-directional by default.
The ordering of these steps is important. The route lookup occurs first to determine the exiting
interface and then NetDefendOS looks for an IP rule that allows the traffic to leave on that interface.
If a rule does not exist then the traffic is dropped.
3.6.1. Security Policies
Chapter 3. Fundamentals
139
Summary of Contents for NetDefend DFL-1660
Page 28: ...1 3 NetDefendOS State Engine Packet Flow Chapter 1 NetDefendOS Overview 28 ...
Page 88: ...2 6 3 Restore to Factory Defaults Chapter 2 Management and Maintenance 88 ...
Page 166: ...3 10 DNS Chapter 3 Fundamentals 166 ...
Page 254: ...4 7 5 Advanced Settings for Transparent Mode Chapter 4 Routing 254 ...
Page 268: ...5 4 IP Pools Chapter 5 DHCP Services 268 ...
Page 368: ...6 7 Blacklisting Hosts and Networks Chapter 6 Security Mechanisms 368 ...
Page 390: ...7 4 7 SAT and FwdFast Rules Chapter 7 Address Translation 390 ...
Page 414: ...8 3 Customizing Authentication HTML Pages Chapter 8 User Authentication 414 ...
Page 490: ...9 8 6 Specific Symptoms Chapter 9 VPN 490 ...
Page 528: ...10 4 6 Setting Up SLB_SAT Rules Chapter 10 Traffic Management 528 ...
Page 544: ...11 7 HA Advanced Settings Chapter 11 High Availability 544 ...
Page 551: ...12 3 5 Limitations Chapter 12 ZoneDefense 551 ...
Page 574: ...Default 512 13 9 Miscellaneous Settings Chapter 13 Advanced Settings 574 ...
Page 575: ...13 9 Miscellaneous Settings Chapter 13 Advanced Settings 575 ...