Moxa V2616A-C5 [31/111] Iptables

V2616A Linux Managing Communications

3-9

MOXA:~# umount /

9. Re-start the apache server.

MOXA:~# /etc/init.d/apache2 restart

ATTENTION

Visit the Apache website at

http://httpd.apache.org/docs/ for more information about setting up Apache

server

IPTABLES

IPTABLES is an administrative tool for setting up, maintaining, and inspecting the Linux kernel’s IP packet filter

rule tables. Several different tables are defined, with each table containing built-in chains and user-defined

chains.

Each chain is a list of rules that apply to a certain type of packet. Each rule specifies what to do with a matching

packet. A rule (such as a jump to a user-defined chain in the same table) is called a target.

The V2616A-LX supports three types of IPTABLES: Filter tables, NAT tables, and Mangle tables.

Filter Table—includes three chains:

• INPUT chain

• OUTPUT chain

• FORWARD chain

NAT Table—includes three chains:

• PREROUTING chain—transfers the destination IP address (DNAT).

• POSTROUTING chain—works after the routing process and before the Ethernet device process to transfer

the source IP address (SNAT).

• OUTPUT chain—produces local packets.

Sub-tables

• Source NAT (SNAT)—changes the first source IP address of the packet.

• Destination NAT (DNAT)—changes the first destination IP address of the packet.

• MASQUERADE—a special form for SNAT. If one host can connect to the Internet, then the 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.

Mangle Table—includes two chains

• PREROUTING chain—pre-processes packets before the routing process.

• OUTPUT chain—processes packets after the routing process.

Mangle tables can have one of three extensions—TTL, MARK, TOS.