Sophie: howto-html-en-20080722-2mdv2010.1 noarch

howto-html-en-20080722-2mdv2010.1.noarch.rpm

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>7.8. ( MASQ and Dynamic IPs ) - Does IP Masquerade work with dynamically 
assigned IP addresses?</H1
><P
><STRONG
>Yes</STRONG
>, it works with either dynamic IP 
addressed assigned by your ISP via either PPP or a DHCP server (common for
Cablemodem and DSL users).  As long as you have a valid Internet IP address, 
it should work.  Of course, static IPs work too.  If you plan on implementing 
a strong IPTABLES, IPCHAINS, or IPFWADM ruleset and/or plan on using a Port 
forwarder, your ruleset will have to be re-executed everytime your IP address 
changes.</P
><P
>So, re-running the rc-firewall-* ruleset really depends on which method you 
get your IP addresses:</P
><P
> <P
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><LI
><P
>PPP:  The /etc/ppp/ip-up script is always run when a PPP connection comes 
up.  Because of this, we can make the rc.firewall-* go get the new PPP IP 
address and update the firewall ruleset.  If the /etc/ppp/ip-up file doesn't 
exist or if does exists, simply edit that file and append a line containing 
the name of your chosen firewall ruleset.  For example, to run the SIMPLE 
IPTABLES ruleset:
   </P
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>/etc/rc.d/rc.firewall-iptables
   </PRE
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>
  </P
></LI
><LI
><P
>DHCP:  If you get your IP address via DHCP, common for Cablemodem and DSL 
users, it's easy get the rc.firewall-* ruleset to run when you get a new 
IP lease.   How this happens depends on what DHCP client your distribution 
uses:
  <P
></P
><UL
><LI
><P
><STRONG
>dhclient</STRONG
> : Most modern Linux distributions 
use dhclient from ISC.  To re-run your specific rc-firewall-* script when your 
system gets a new IP address, add the following line to the 
/etc/dhclient-exit-hooks file.  Please note that this example is loging the 
SIMPLE IPTABLES ruleset.  Please use the correct rc.firewall-* name for your 
specific setup:
    <TABLE
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>/etc/rc.d/rc.firewall-iptables
    </PRE
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>
    </P
></LI
><LI
><P
><STRONG
>pump</STRONG
> : Many older Redhat distributions use 
this DHCP client.  To re-run the rc-firewall-* script when your system gets a 
new IP address, add the following line to the /etc/pump.conf file.  Please 
note that this example is loading the SIMPLE IPTABLES ruleset.  Please use the 
correct rc.firewall-* name for your specific setup:
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>script /etc/rc.d/rc.firewall-iptables
    </PRE
></FONT
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>
    </P
></LI
><LI
><P
><STRONG
>dhcpcd</STRONG
> : Many older distros use this DHCP 
client.  To re-run the rc-firewall-* script when your system gets a new IP 
address depends on which verion of dhcpcd you're using.  
    </P
><P
>For newer dhcpcd client versions, append the following line to the 
/etc/dhcpcd-[interface].exe file.  Please note that you have to replace the 
[interface] text with the name of your Interface connecting to the Internet.
For this example, we are going run the SIMPLE IPTABLES ruleset against the
eth0 interface by editing the /etc/dhcpc/dhcpcd-eth0.exe file:
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>/etc/rc.d/rc.firewall-iptables
     </PRE
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>
    </P
><P
>For old dhcpcd client versions, you need to figure out what script starts up
dhcpcd (depends on the Linux distribution and it's version).  From there, you 
need to replace the specific dhcpcd line with the folling line with the 
correct Internet-facing interface name.  For this example, dhcpcd will run
the SIMPLE IPTABLES ruleset against the eth0 interface: 
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>dhcpcd -c /etc/rc.d/rc.firewall eth0
    </PRE
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>
    </P
></LI
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>
  </P
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><P
>Please also see the top of 
<A
HREF="http://www.ecst.csuchico.edu/~dranch/LINUX/index-linux.html#TrinityOS"
TARGET="_top"
>TrinityOS - Section 10</A
> 
for additional help with strong firewall rulesets and Dynamic IP addresses.  </P
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