Novell LINUX ENTERPRISE SERVER 10 - INSTALLATION AND ADMINISTRATION 11-05-2007, Руководство по установке

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nat
This table defines any changes to the source and target addresses of packets. Using
these functions also allows you to implement masquerading, which is a special
case of NAT used to link a private network with the Internet.
mangle
The rules held in this table make it possible to manipulate values stored in IP
headers (such as the type of service).
Figure 43.1 iptables: A Packet's Possible Paths
Routing
Routing
in the local
system
Processes
outgoing packet
incoming packet
filter
nat
mangle
POSTROUTING
PREROUTING
nat
mangle
FORWARD
mangle
filter
INPUT
mangle
filter
OUTPUT
nat
mangle
These tables contain several predefined chains to match packets:
PREROUTING
This chain is applied to incoming packets.
INPUT
This chain is applied to packets destined for the system's internal processes.
FORWARD
This chain is applied to packets that are only routed through the system.
OUTPUT
This chain is applied to packets originating from the system itself.
818 Installation and Administration