Linuxdoc Linux Questions
Click here to ask our community of linux experts!
Custom Search
Next Previous Contents

2. Firewall Configuration

This howto assumes you already configured your kernel to support IP masquerade. See references below for information on configuring your kernel for a linux firewall.

2.1 VPN Network Diagram

This setup uses a star/hub configuration. It will set up a cipe connection from Machine A to Machine B and another from Machine A to Machine C.



                   Machine A 
                eth0: 192.168.1.1 
                eth1: real ip 1 
               /               \ 
              /                 \ 
     Machine B                  Machine C 
   eth0: 192.168.2.1           eth0:192.168.3.1 
   eth1: real ip 2             eth1: real ip 3 


2.2 A little reference



eth0 is the local network (fake address) 
eth1 is the internet address (real address) 

Port A is any valid port you would like to choose 
Port B is any other valid port you would like to choose 

Key A is any valid key you would like to choose  (read cipe doc for info) 
Key B is any valid key you would like to choose 


2.3 Additional notes about scripts and the VPN

The ip-up scripts currently only allow class c traffic through the cipe interface. If you wish for machine B to communicate with Machine C then you will need to change the appropriate ip-up and ip-down scripts. Specifically, you need to change the ptpaddr and myaddr netmasks. There are two ip-up scripts, one for ipchains and one for ipfwadm. Same with the ip-down scripts. Change the appropriate incoming, outgoing, and forwarding cipe interface firewall rules netmask from /24 to /16. Any cipe firewall rule changes you make in ip-up for ipfwadm, make sure the ip-down script reflects the change so it will be properly removed from the list when the interface goes down. For the ipchains file, anything added in a chain does not need ip-down reflection since ip-down will flush all the rules in the user defined chain.

You will also need to uncomment the network route in the rc.cipe for Machine B and C that adds each others network to their route table.


Next Previous Contents