Network Configuration

Installing your system as a standalone networked system assures that most network configuration has been done by the install process. You can improve the ability of the SPARCstation Voyager to operate in nomadic mode by adding frequently accessed remote host names to the local hosts database and by preventing your machine from acting as a router.

Hostname to IP Address Mapping

Because the system won't always have access to the NIS/NIS+/DNS databases, hostname to IP address mapping, requested by programs such as sendmail and PPP (aspppd), may fail when the system is disconnected, if the local /etc/inet/hosts file does not contain a requested entry. Adding frequently accessed remote host names to the /etc/inet/hosts file will minimize such failures.

Example 5-1 Internet Host Table

#
# Internet host table
#
127.0.0.1	localhost loghost
224.0.0.0	multicast-ip
#
# This machine
#
192.9.10.5	voyager
#
# Frequently accessed hosts
#
192.9.11.113	sparctreker
192.9.11.126	parhelion
192.9.20.30	datehost
192.9.60.81	applserver
192.9.7.81	cosmos mailhost

You may prefer to use admintool to edit the /etc/init/hosts file.

Generally you won't have to put more than a dozen or so map entries in the /etc/inet/hosts file. After initially populating the file with entries that you think you'll need, you can then add entries as you discover them (usually because a command fails, producing a message such as "unknown host zargon").

IP Forwarding and Network Routing

If you plan to use PPP to create a wide area network connection over telephone lines, it may be necessary to disable IP forwarding. IP forwarding is enabled at boot time when the system detects more than one interface (i.e. Ethernet and PPP). In this case, the system will also be configured as a router. This is undesirable because other routers on the network will attempt to route network traffic through your system. In addition to the performance impact on your system and the network, it is possible to cause network routing failures that are difficult to detect and correct.

To avoid this, establish an /etc/defaultrouter file that contains the name of one of the routers serving your network or subnetwork. You can determine a candidate router by inspecting the route table with the netstat command while your system is connected to the network.

# netstat -r
Routing Table:
 Destination          Gateway           Flags  Ref   Use   Interface
----------------- ------------------ ----- ---- ------ ---------
localhost	localhost	UH	0	20	lo0
slivan	ethr17a-11	UGH	0	0
single	ethr17a-11	UGH	0	0
mtnview	ethr17a-11	UG	0	9
net-eng-bb	fddi17b-11	UG	0	3961
net15-067-n	ethr17a-11	UG	0	0
net17-007-n	goldigger-eng	UG	0	1291
net19-174-n	fddi17b-11	UG	0	0
net17-083-n	shunt-116	UG	0	0
net21-244-n	ethr17a-11	UG	0	0
net18-148-n	ethr17a-11	UG	0	0
milpitas	ethr17a-11	UG	0	42
net11-144-n	voyager	U	2	3788	le0
224.0.0.0	voyager	U	4	0	le0

Since most routes in the above example are directed through gateway ethr17a-11, choose ethr17a-11 as your default router by creating an /etc/defaultrouter file with that name in it. The file should contain only the name of the selected default router, as in:

ethr17a-11

Note that when you configure your system to use a default router, you sacrifice the dynamic routing capability that Solaris provides. If you don't want to do this, edit the /etc/init.d/inetinit file. Change the test for "routerhood" to always fail: in /etc/init.d/inetinit, change

if [ $numifs -gt 2 -o $numptptifs -gt 0 -o -f /etc/gateways ]; then

to:

if [ `/bin/false` ]; then	# Never be a router

The disadvantage of this method is that your system can receive Routing Information Packets (RIP) across a PPP connection, which limits the available bandwidth.