HOWTO: multiple default routes

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Thanks to phoenix help I was able to setup multiple default routes, or a default route per network/interface to be precise, in Debian/Linux it is as simple as that:

/etc/network/interfaces
Code:

iface eth0 inet static    address 10.0.0.1    netmask 255.255.255.0    gateway 10.0.0.254iface eth1 inet static    address 20.0.0.1    netmask 255.255.255.0    gateway 20.0.0.254

That would be example topology (but more then 2 interfaces is also possible).
Code:

 NETWORK0                      NETWORK1         \                            /          \                          /           \                        /            \                      /             \                    /          ROUTER0             ROUTER1          10.0.0.254          20.0.0.254              \                  /        +------\----------------/------+        |       \              /       |        |       em0          em1       |        |    10.0.0.1     20.0.0.1     |        |                              |        |         FREEBSD BOX          |        |                              |        +------------------------------+

Now, You can not use the ‘casual‘ defaultrouter="X" cause it will be only for one network.

We will have to use setfib(1) to create two (or more) separete routing tables per network/interface.

Add these lines to /boot/loader.conf file:
Code:

ipfw_load="YES"net.fibs=16

It will unfortunately require kernel recompile, but its not as that hard:
Code:

# cd /usr/src/sys/$( uname -m )/conf# cp GENERIC /root/ROUTES# ln -s /root/ROUTES# echo "options ROUTETABLES=16" >> ROUTES# cd /usr/src# make NO_MODULES=1 kernel KERNCONF=ROUTES KODIR=/boot/routes# mv /boot/routes/kernel /boot/kernel/kernel# reboot

We can of course set 2 instead of 16, but You will at least have to recompile Your kernel again and reboot which is not very handy ...

Nest set your networks/interfaces as usual in /etc/rc.conf file:
Code:

ifconfig_em0="inet 10.0.0.1/24"ifconfig_em1="inet 20.0.0.1/24"# check /etc/rc.local for default routes

All the rest configuration resides in /etc/rc.local file:
Code:

# define default routessetfib 0 route delete defaultsetfib 0 route add    default 10.0.0.254setfib 1 route delete defaultsetfib 1 route add    default 20.0.0.254# assing route tables to interfacesipfw -f flushipfw add allow    ip from any to any via lo0ipfw add setfib 1 ip from any to any via em0ipfw add setfib 0 ip from any to any via em1ipfw add allow    ip from any to any

These would be handy for restarting:
Code:

# /etc/rc.d/netif restart# /etc/rc.d/local restart

來源： <http://daemonforums.org/showthread.php?t=4610> 

來自為知筆記(Wiz)

HOWTO: multiple default routes