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:*'''OUTPUT''': Packets leaving current Linux server
:*'''FORWARD''': Packets being routed between Linux servers
Let's get some practice using the iptables command as we introduce concepts such as listing CHAIN rules, and clearing the CHAIN rules:
# Issue the following command to list the existing iptables policy rules: <b><code><span style="pointer-events: none;cursor: default;color:#3366CC;font-size:1.2em;">iptables -L</span></code></b>.
# Were there already iptables policy rules that already existed by default?
Before we proceed, we need to understand various methods to list iptables rules:
<table width="100%" cellpadding="10" cellspacing="0" border="1">
<tr>
<td width="30%">'''iptables -L'''</td><td>List all iptables rules (eg. INPUT, OUTPUT. FORWARD, and any customized chains (if any)</td>
<td>'''iptables -L -v'''</td><td>Verbosely List all iptables rules including information such as total size of packets affected by rules</td>
</tr><tr>
<td>'''iptables -L CHAIN-NAME'''</td><td>List all iptables rules for that particular chain-name for less clutter (eg. INPUT or OUTPUT, etc)</td>
</tr>
</table>
# Issue the following command to reset the iptables policy rules: <b><code><span style="pointer-events: none;cursor: default;color:#3366CC;font-size:1.2em;">iptables -F</span></code></b>.
# Issue the '''iptables -L''' command to verify that the iptables rules have been reset.
