14. Client: Configure Networking

Now we should setup the networking on our client box. Let's assume that we've configured the external network and that it works. Now we will configure the internal interface of the client to service our intranet.

14.1. Interface

We need to first bring up the internal network interface. To do this, add the following to your /etc/rc.d/rc.inet1 (or equivalent) file:

For 2.0 Kernels:

/sbin/ifconfig eth1 broadcast netmask
/sbin/route add -net netmask dev eth1

For 2.2 Kernels:

/sbin/ifconfig eth1 broadcast netmask

14.2. Filter rules

To set up the remote office, we will want to set up our filter rules that allow traffic to go both directions through the tunnel. Add the following lines to your /etc/rc.d/rc.inet1 (or equivalent) file:

For 2.0 kernels:

/sbin/ipfwadm -F -f
/sbin/ipfwadm -F -p deny
/sbin/ipfwadm -F -a accept -b -S -D

For 2.2 kernels:

/sbin/ipchains -F forward
/sbin/ipchains -P forward DENY
/sbin/ipchains -A forward -j ACCEPT -b -s -d

You may have noticed that these lines look like what we have on the server. That's because they are the same. These rules just say where traffic is allowed to go between these two networks.

14.3. Routing

The only extra routes that are needed are created by the script that bring the tunnel up.