Configuring TCP/IP on Solaris - Network Databases and nsswitch.conf File

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Introduction

The network databases are files that provide information needed to configure the network. The network databases are: As part of the configuration process, you edit the hosts database and the netmasks database, if your network is subnetted. Two network databases, bootparams and ethers, are used to configure machines as network clients. The remaining databases are used by the operating system and seldom require editing.

Although it is not a network database, the nsswitch.conf file needs to be configured along with the relevant network databases. nsswitch.conf specifies which name service to use for a particular machine: NIS, NIS+, DNS, or local files.

How Name Services Affect Network Databases

Your network database takes a form that depends on the type of name service you select for your network. For example, the hosts database contains, at minimum, the host name and IP address of the local machine and any network interfaces directly connected to the local machine. However, the hosts database could contain other IP addresses and host names, depending on the type of name service on your network.

The network databases are used as follows:

Note - DNS boot and data files do not correspond directly to the network databases.

Network Database Local Files NIS+ Tables NIS Maps
hosts /etc/inet/hosts hosts.ord_dir hosts.byaddr
hosts.byname
netmasks /etc/inet/netmasks netmasks.ord_dir netmasks.byaddr
ethers /etc/ethers ethers.ord_dir ethers.byname
ethers.byaddr
bootparams /etc/bootparams bootparams.ord_dir bootparams
protocols /etc/inet/protocols protocols.ord_dir protocols.byname
protocols.bynumber
services /etc/inet/services services.ord_dir services.byname
networks /etc/inet/networks networks.ord_dir networks.byaddr
networks.byname

nsswitch.conf File - Specifying Which Name Service to Use

The /etc/nsswitch.conf file defines the search order of the network databases. The Solaris installation program creates a default /etc/nsswitch.conf file for the local machine, based on the name service you indicate during the installation process. If you selected the 'None' option, indicating local files for name service, the resulting nsswitch.conf file resembles the following example:

nsswitch.conf for Networks Using Files for Name Service
# /etc/nsswitch.files:
#
# An example file that could be copied over to /etc/nsswitch.conf;
# it does not use any naming service.
#
# "hosts:" and "services:" in this file are used only if the
# /etc/netconfig file contains "switch.so" as a
# nametoaddr library for "inet" transports.
passwd: files
group: files
hosts: files
networks: files
protocols: files
rpc: files
ethers: files
netmasks: files
bootparams: files
publickey: files
# At present there isn't a 'files' backend for netgroup; the
# system will figure it out pretty quickly,
# and won't use netgroups at all.
netgroup: files
automount: files
aliases: files
services: files
sendmailvars: files

The nsswitch.conf(4) man page describes the file in detail. Its basic syntax is:

database name-service-to-search

The database field can list one of many types of databases searched by the operating system. For example, it could indicate a database affecting users, such as passwd or aliases, or a network database. The parameter name-service-to-search can have the values files, nis, or nis+ for the network databases. (The hosts database can also have dns as a name service to search.) You can also list more than one name service, such as nis+ and files.

In the above example, the only search option indicated is files. Therefore, the local machine gets security and automounting information, in addition to network database information, from files located in its /etc and /etc/inet directories.

Changing nsswitch.conf

The /etc directory contains the nsswitch.conf file created by the Solaris installation program. It also contains template files for the following name services: If you want to change from one name service to another, you can copy the appropriate template to nsswitch.conf. You can also selectively edit the nsswitch.conf file, and change the default name service to search for individual databases.

For example, on a network running NIS, you might have to change the nsswitch.conf file on diskless clients. The search path for the bootparams and ethers databases must list files as the first option, and nis. The example below shows the correct search paths.

nsswitch.conf for a Diskless Client on a Network Running NIS
## /etc/nsswitch.conf:#
.
.
passwd: files nis
group: file nis
# consult /etc "files" only if nis is down.
hosts: nis [NOTFOUND=return] files
networks: nis [NOTFOUND=return] files
protocols: nis [NOTFOUND=return] files
rpc: nis [NOTFOUND=return] files
ethers: files [NOTFOUND=return] nis
netmasks: nis [NOTFOUND=return] files
bootparams: files [NOTFOUND=return] nis
publickey: nis
netgroup: nis
automount: files nis
aliases: files nis
# for efficient getservbyname() avoid nis
services: files nis
sendmailvars: files

bootparams Database

The bootparams database contains information used by diskless clients and machines configured to boot in the network client mode. You need to edit it if your network will have network clients. The database is built from information entered into the /etc/bootparams file.

The bootparams(4) man page contains complete syntax for this database. Its basic syntax is:

    machine-name file-key-server-name:pathname
For each diskless or network client machine, the entry might contain the following information: the name of the client, a list of keys, the names of servers, and path names.

The first item of each entry is the name of the client machine. Next is a list of keys, names of servers, and path names, separated by tab characters. All items but the first are optional. The database can contain a wildcard entry that will be matched by all clients. Here is an example:

bootparams Database
myclient root=myserver : /nfsroot/myclient \
swap=myserver : /nfsswap//myclient \
dump=myserver : /nfsdump/myclient

In this example the term dump=: tells diskless hosts not to look for a dump file.

Wildcard Entry for bootparams
In most cases, you will want to use the wildcard entry when editing the bootparams database to support diskless clients. This entry is:

    * root=server:/path dump=:
The asterisk (*) wildcard indicates that this entry applies to all clients not specifically named within the bootparams database.

ethers Database

The ethers database is built from information entered into the /etc/ethers file. It associates host names to their Ethernet addresses. You need to create an ethers database only if you are running the RARP daemon; that is, if you are configuring network clients or diskless machines.

RARP uses the file to map Ethernet addresses to IP addresses. If you are running the RARP daemon in.rarpd, you need to set up the ethers file and maintain it on all hosts running the daemon to reflect changes to the network.

The ethers(4) man page contains complete syntax information for this database. Its basic format is:

Ethernet-address hostname #comment
Ethernet-address is the Ethernet address of the host.
hostname is the official name of the host.
#comment is any kind of note you want to append to an entry in the file.

The equipment manufacturer provides the Ethernet address. If a machine does not display the Ethernet address when you power up, see your hardware manuals for assistance.

When adding entries to the ethers database, make sure that host names correspond to the primary names in the hosts database, not to the nicknames, as shown in the following example:

Entries in the ethers Database
8:0:20:1:40:16 fayoum
8:0:20:1:40:15 nubian
8:0:20:1:40:7 sahara # This is a comment
8:0:20:1:40:14 tenere

Other Network Databases

The remaining network databases seldom need to be edited.

networks database Database

The networks database associates network names with network numbers, enabling some applications to use and display names rather than numbers. The networks database is based on information in the /etc/inet/networks file. It contains the names of all networks to which your network connects via routers.

The Solaris installation program sets up the initial networks database. The only time you need to update it is when you add a new network to your existing network topology.

The networks(4) man page contains full syntax information for /etc/inet/networks. Here is its basic format:

  network-name network-number nickname(s) # comment
  network-name is the official name for the network.
  network-number is the number assigned by the InterNIC.
  nickname is any other name by which the network is known.
  #comment is any kind of note you want to append to an entry in the file.
It is particularly important that you maintain the networks file. The netstat program uses the information in this database to produce status tables. The example shows a sample /etc/networks file:

/etc/networks File
#ident "@(#)networks 1.4 92/07/14 SMI" /* SVr4.0 1.1 */
#
# The networks file associates Internet Protocol (IP) network
numbers with network names. The format of this file is:
#
# network-name network-number nicnames . . .
# The loopback network is used only for intra-machine
communication
#loopback 127
# Internet networks
#
arpanet 10 arpa # Historical
ucb-ether 46 ucbether
#
# local networks
eng 193.9.0 #engineering
acc 193.9.1 #accounting
prog 193.9.2 #programming

protocols Database

The protocols database lists the TCP/IP protocols installed on your system and their numbers; the Solaris installation program automatically creates it. It is rare when this file requires administrative handling.

The protocols database contains the names of the TCP/IP protocols installed on the system. Its syntax is completely described in the protocols(4) man page. The example below shows an example of the /etc/inet/protocols file:

/etc/inet/protocols File
#
# Internet (IP) protocols
#
ip 0 IP # internet protocol, pseudo protocol number
icmp 1 ICMP # internet control message protocol
tcp 6 TCP # transmission control protocol
udp 17 UDP # user datagram protocol

services Database

The services database lists the names of TCP and UDP services and their well known port numbers; it is used by programs that call network services. The Solaris installation automatically creates the services database; it generally requires no administrative handling.

The services(4) man page contains complete syntax information. The example below shows an excerpt from a typical /etc/inet/services file:

/etc/inet/services File
#
# Network services
#
echo 7/udp
echo 7/tcp
discard 9/udp sink null
discard 11/tcp
daytime 13/udp
daytime 13/tcp
netstat 15/tcp
ftp-data 20/tcp
ftp 21/tcp
telnet 23/tcp
time 37/tcp timeserver
time 37/udp timeserver
name 42/udp nameserver
whois 43/tcp nickname



Last modified on: Saturday, 18-Sep-2010 17:27:43 EDT
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