Static Routing Lab

protocol device {
    scan time 10;
}

Next, the kernel section tells us what to do with the kernel’s routing table:

protocol kernel {
    persist;
    metric 64;  # Use explicit kernel route metric to avoid collisions
            # with non-BIRD routes in the kernel routing table
    scan time 20;
    import all;
    export all; # Actually insert routes into the kernel routing table
}

The kernel section isn’t particularly important until we implement some sort of dynamic routing, as all of these options are used for keeping track of dynamic routes. Put them in, but they won’t be important for now. Next, we have the direct section:

protocol direct {
    interface "ens5";
    interface "ens2";
}

This section autogenerates routes based off of the IPs of the interfaces. Finally, we have the static section:

protocol static {
    route 0.0.0.0/0 via 172.30.105.1;
}

This section tells all traffic other than that on the LAN interfaces to use the hub as the gateway.

similar to service networking restart bird can be restarted with service bird restart but that can cause unnecessary outages so that’s why we use “birdc configure soft”

Surprisingly enough, that’s all we have to do in bird. We do, however, have to edit a kernel module to make sure we can pass ipv4 traffic through the bird VM. This module is called net.ipv4.ip_forward and without it, no routing would work. To enable it, edit /etc/sysctl.conf and uncomment the “net.ipv4.ip_forward=1” line.

Now that routing’s out of the way, we can add DHCP. For this, we will use a simple ISC (Internet Systems Consortium) DHCP server. The configuration for this is all in /etc/dhcp/dhcpd.conf.

At the top of the file, we define the domain name and DNS server for all the DHCP clients.

option domain-name "local.test.spoke1";
option domain-name-servers 172.30.104.1;

Set the domain name as whatever is appropriate for you. We are using 172.30.104.1 (our firewall) as the DNS server for this example, but you can just as easily use something else like 8.8.8.8. Next, we get to the actual subnet-specific settings:

subnet 172.30.106.0 netmask 255.255.255.0 {
    range 172.30.106.100 172.30.106.200;
    option subnet-mask 255.255.255.0;
    option broadcast-address 172.30.106.255;
    option routers 172.30.106.1;
}

First, we define the network to use as 172.30.106.0/24. Next, we say that IP addresses will be distributed from 172.30.106.100-200. The subnet mask defines the size of the network, and the broadcast tells which hosts to broadcast requests to. Finally, we use the IP of the router as the router option.

Now, we just have to set a few basic rules and we’re done:

default-lease-time 600;
max-lease-time 7200;
authoritative;

The first two lines define how long to keep DHCP leases for. The default is 600 seconds, but if a client requests, it can go up to 7200 seconds. Authoritative says that this is the only DHCP server on the network. That’s it for dhcpd.conf!

We need to make one last change and then we can test everything out. Open up /etc/default/isc-dhcp-server.

At the end, there should be a line like so:

INTERFACESv4=""

Add the LAN interface name in those quotes. Mine looks like

INTERFACESv4="ens2"

Note that yours might not be the same.

Finally, in order to ensure that all of these services are running and using the current configuration run these commands:

Before you run those commands test the DHCP server with the command: