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There are a few things that are unclear in all the documentation on 
firewalling and masquerading that if they had been stated clearly I would 
have had my network up and running a lot sooner and without the headaches. 

First, if your external interface is ppp, then you must not start the 
firewall/masqueing on bootup or before the ppp interface is initialized. The 
the only way that the firewall can get the correct dynamic IP address is 
after it has been assigned. The firewall rules are static, and if it cannot 
find the interface when initialized, it will not find it later. The correct 
place for initializing the firewall rules is in /etc/.../ip-up.local, usually 
as the last line. When ppp goes down you need not run the firewall, so put a 
stop command in /etc/.../ip-down.local. Second, dynamic addresses assigned by 
ISPs to ppp interfaces are not not done by DHCP, so if you've set your 
firewall rules to see your address by DHCP it will not work. You can, 
however, run a DHCP server on your internal network to assign your local 
computers dynamic IP addresses, but if you only have a few machines its best 
to assign them fixed addresses and not take up resources and cause more 
complications by running a DHCP server. 

If any of your local machines is a Windows machine be sure to enable DSP in 
your Networking applet in Control-Pannel - assign at least a couple of 
nameserver addresses, your local one and perhaps your ISP's. You can run a 
caching nameserver that's easy to set up - get the program from 
Freshmeat.net, Rufus.w3.org (RPM) or it may be included in your UNIX (Linux) 
distribution. This program can also be run from ip-up.local and stopped from 
ip-down.local if you do not need local DNS services. 

Of course, if your external connection to the Internet is by ethernet you 
should start the firewall/masqueing on bootup unless your ethernet interface 
is not recognized then. In short, the interface must be up and assigned an IP 
address before the firewall is initialized. If your local IP address is 
assigned by DHCP, as in DSL, then you need to tell your firewall that. The 
firewall may have to be reinitialized if your IP address changes. 

Be sure that ip_dynamic_addr, ip_forwarding, etc., and the appropriate 
modules loaded - things that are well-documented to make masqueing work - are 
compiled into the kernel and turned on. These should be included in the 
firewall script. 

You don't need any complicated routing tables or protocols. The default 
gateway should be assigned when your ppp connection is made. If your local 
network is functional by TCP/IP, then you should be able to masq it. 

I hope this helps. 

-- 
[EMAIL PROTECTED] <Stuart Norman>
Censorship is the ultimate obscenity.

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