Moxa Technologies EM-1240-LX Define policy rules, and Append or delete rules, Usage, Examples

EM-1240-LX User’s Manual Configuring EM-1240-LX

The EM-1240-LX supports the following sub-modules. Be sure to use the module that matches your application.

ip_conntrack	ipt_MARK
ip_conntrack_ftp	ipt_MASQUERADE
ipt_conntrack_irc	ipt_MIRROT
ip_nat_ftp	ipt_REDIRECT
ip_nat_irc	ipt_REJECT
ip_nat_snmp_basic	ipt_TCPMSS
ip_queue	ipt_TOS

ipt_ah ipt_esp ipt_length ipt_limit ipt_mac ipt_mark ipt_multiport ipt_owner

ipt_state

ipt_tcpmss

ipt_tos

ipt_ttl

ipt_unclean

NOTE The EM-1240-LX does NOT support IPV6 and ipchains.

Use iptables, iptables-restore, iptables-save to maintain the database.

NOTE IPTABLES supports packet filtering or NAT. Take care when setting up the IPTABLES rules. If the rules are not correct, remote hosts that connect via a LAN or PPP may be denied access. We recommend using the Serial Console to set up IPTABLES.

Click on the following links for more information about iptables.

http://www.linuxguruz.com/iptables/

http://www.netfilter.org/documentation/HOWTO//packet-filtering-HOWTO.html

Since the IPTABLES command is very complex, to illustrate the IPTABLES syntax we have divided our discussion of the various rules into three categories: Observe and erase chain rules,

Define policy rules, and Append or delete rules.

Observe and erase chain rules

Usage:

# iptables [-t tables] [-L] [-n]

-t tables:	Table to manipulate (default: ‘filter’); example: nat or filter.
-L [chain]: List	List all rules in selected chains. If no chain is selected, all chains are listed.
-n:	Numeric output of addresses and ports.

# iptables [-t tables] [-FXZ]

-F: Flush the selected chain (all the chains in the table if none is listed).

-X: Delete the specified user-defined chain.

-Z: Set the packet and byte counters in all chains to zero.

Examples:

# iptables -L -n

In this example, since we do not use the -t parameter, the system uses the default ‘filter’ table. Three chains are included: INPUT, OUTPUT, and FORWARD. INPUT chains are accepted automatically, and all connections are accepted without being filtered.

#iptables –F #iptables –X #iptables –Z

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