User`s manual
Table Of Contents
- 1. Introduction
- 2. Getting Started
- Powering on the W406-LX
- Connecting the W406-LX to a PC
- Configuring the Ethernet Interface
- USB Port for Expansion
- SD Socket for Storage Expansion
- Setting Up the Wireless Module
- Configuring the SIM Card
- Entering the PIN Code
- Verifying the SIM Card Status
- Enabling or Disabling the PIN Code Authentication
- Changing the PIN Code
- Unlocking the SIM Card
- Connecting to the Internet
- Reconnecting to the Internet
- Disconnecting from the Internet
- Detecting an Internet Connection Error
- Sending and Reading an SMS Message
- Deleting an SMS Message
- Test Program—Developing Hello.c
- 3. Managing Embedded Linux
- 4. Managing Communications
- 5. Development Tool Chains
- 6. Programmer’s Guide
- 7. Software Lock
- A. System Commands
W406-LX User’s Manual Managing Communications
4-9
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
Define policy for chain rules
Usage:
# iptables [-t tables] [-P] [INPUT, OUTPUT, FORWARD, PREROUTING, OUTPUT, POSTROUTING]
[ACCEPT, DROP]
-P: Set the policy for the chain to the given target.
INPUT: For packets coming into the W406-LX.
OUTPUT: For locally-generated packets.
FORWARD: For packets routed out through the W406-LX.
PREROUTING: To alter packets as soon as they come in.
POSTROUTING: To alter packets as they are about to be sent out.
Examples:
#iptables –P INPUT DROP
#iptables –P OUTPUT ACCEPT
#iptables –P FORWARD ACCEPT
#iptables –t nat –P PREROUTING ACCEPT
#iptables –t nat –P OUTPUT ACCEPT
#iptables -t nat –P POSTROUTING ACCEPT
In this example, the policy accepts outgoing packets and denies incoming packets.