Configuring a Router on a Running System

The decision to start the routing daemon in.routed and the router discovery protocol daemon in.rdisc is taken when the startup script /etc/rc2.d/S69inet executes. You can also configure your system to act as a router without needing to reboot.

To configure a system as a router, it must have multiple network interfaces connected and configured.

Follow these steps to configure your system as a router:

1. Be sure the files /etc/defaultrouter and /etc/notrouter do not exist. If they do, remove them. Also, make sure that all network interfaces are correctly configured and have entries present in the /etc/inet/ hosts file.

2. You need to enable the forwarding of IP packets, which is done using the ndd command. You can enable IP forwarding on all network interfaces or just a specific interface. To enable IP forwarding on all the network interfaces, enter the following:

    ultra10# ndd -set /dev/ip ip_forwarding 1 

   Setting the value of the ip_forwarding parameter to 1 enables forwarding, and setting it to disables it.

   To enable IP forwarding on only a specific network interface, such as hme0 , enter the following:

    ultra10# ndd -set /dev/ip hme0:ip_forwarding 1 

3. Stop and restart the in.routed process, if it is running, as follows :

    ultra10# pkill in.routed; /usr/sbin/in.routed -s 

4. Stop and restart the in.rdisc process, if it is running, as follows:

    ultra10# pkill in.rdisc; /usr/sbin/in.rdisc -r 

You might also want to disable routing on a system with multiple network interfaces, which is often called a multihomed host . A system with multiple interfaces is automatically considered to be a router at boot time unless the file /etc/notrouter exists. To stop a system from functioning as a router, simply disable the ip_forwarding network parameter by setting it to , using the ndd command, and then create the file /etc/notrouter as follows:

 ultra10# ndd -set /dev/ip ip_forwarding 0 ultra10# touch /etc/notrouter 

When the system reboots, it will not function as a router.