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Packet Filtering using ipchains
DHCP server. The default option is to NOT set the host name of the host to the hostname parameter sent
by the DHCP server.
•
R This option prevents dhcpcd from replacing the existing /etc/resolv.conf file.
The user should not modify the -c /sbin/handle_dhcp option.
Packet Filtering using ipchains
The PortServer CM uses the Linux utility ipchains to filter IP packets entering, leaving and passing through
its interfaces. An ipchains tutorial is beyond the scope of this manual. For more information on ipchains, see
the ipchains man page (not included with the PortServer CM) or the howto http://netfilter.filewatcher.org/
ipchains/HOWTO.html.
The syntax of the ipchains command is:
ipchains - command chain [-s source] [-d destination] [-p protocol] [-j target]
[-i interface]
where
command
is one of the following:
•
A - Add a condition or rule to the end of the chain. Note that the order in which a condition appears in a
chain can modify its application and the first rule added to a chain is processed first, etc.
•
D - Delete a condition from the chain. The condition must match exactly with the command’s arguments
to be deleted.
•
R- Replace a condition in the chain.
•
I - Insert a condition in a specified location in the chain.
•
L - List all conditions in the chain.
•
F - Flush (remove) all conditions in the chain.
•
N - Create a new chain.
•
X - Deletes a user-created chain