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UC-7110 Series User’s Manual Configuring UC-7110
4-4
OUTPUT chain—produces local packets
sub-tables
Source NAT (SNAT)—changes the first source packet IP address
Destination NAT (DNAT)—changes the first destination packet IP address
MASQUERADE—a special form for SNAT. If one host can connect to the Internet, then
other computers that connect to this host can connect to the Internet when the computer
does not have an actual IP address.
REDIRECT—a special form of DNAT that re-sends packets to a local host independent
of the destination IP address.
C. Mangle Table—includes two chains
PREROUTING chain—pre-processes packets before the routing process.
OUTPUT chain—processes packets after the routing process.
It has three extensions—TTL, MARK, TOS.
The following figure shows the IPTABLES hierarchy.