Which Sat Rule Is Executed If Several Are Matching; Sat And Fwdfast Rules - D-Link NetDefend DFL-210 User Manual

7.2.6. Which SAT Rule is executed if
several are matching?
designed to read and/or alter application data. These are commonly referred to as Application Layer
Gateways or Application Layer Filters. NetDefendOS supports a number of such Application Layer
Gateways and for more information please see Section 6.2, "Application Layer Gateways".

7.2.6. Which SAT Rule is executed if several are matching?

NetDefendOS does not terminate the rule-set lookup upon finding a matching SAT rule. Instead, it
continues to search for a matching Allow, NAT or FwdFast rule. Only when it has found such a
matching rule does the firewall execute the static address translation.
Despite this, the first matching SAT rule found for each address is the one that will be carried out.
"Each address" above means that two SAT rules can be in effect at the same time on the same con-
nection, provided that one is translating the sender address whilst the other is translating the destina-
tion address.
# Action Src Iface
1 SAT any
2 SAT lan
The two above rules may both be carried out concurrently on the same connection. In this instance,
internal sender addresses will be translated to addresses in the "pubnet" in a 1:1 relation. In addition,
if anyone tries to connect to the public address of the web server, the destination address will be
changed to its private address.
# Action Src Iface
1 SAT lan
2 SAT any
In this instance, both rules are set to translate the destination address, meaning that only one of them
will be carried out. If an attempt is made internally to communicate with the web servers public ad-
dress, it will instead be redirected to an intranet server. If any other attempt is made to communicate
with the web servers public address, it will be redirected to the private address of the publicly ac-
cessible web server.
Again, note that the above rules require a matching Allow rule at a later point in the rule-set in order
to work.

7.2.7. SAT and FwdFast Rules

It is possible to employ static address translation in conjunction with FwdFast rules, although return
traffic must be explicitly granted and translated.
The following rules make up a working example of static address translation using FwdFast rules to
a web server located on an internal network:
# Action
1 SAT
2 SAT
3 FwdFast
4 FwdFast
We add a NAT rule to allow connections from the internal network to the Internet:
# Action
5 NAT
What happens now?
• External traffic to wan_ip:80 will match rules 1 and 3, and will be sent to wwwsrv. Correct.
Src Net Dest Iface
all-nets core
lannet all-nets
Src Net Dest Iface
lannet wwwsrv_pub
all-nets wwwsrv_pub
Src Iface Src Net Dest Iface
any all-nets core
lan wwwsrv any
any all-nets core
lan wwwsrv any
Src Iface Src Net Dest Iface
lan lannet any
Dest Net Parameters
wwwsrv_pub TCP 80-85 SETDEST 192.168.0.50 1080
Standard SETSRC pubnet
Dest Net Parameters
TCP 80-85 SETDEST intrasrv 1080
TCP 80-85 SETDEST wwwsrv-priv 1080
Dest Net
wan_ip
all-nets
wan_ip
all-nets
Dest Net
all-nets
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Chapter 7. Address Translation
Parameters
http SETDEST wwwsrv 80
80 -> All SETSRC wan_ip 80
http
80 -> All
Parameters
All