The /etc/netconfig file

The system administrator is responsible for maintaining the network configuration database file /etc/netconfig. Entries in the netconfig file contain the following fields in the order shown here:

network_id semantics flags protofamily protoname device nametoaddr_libs

The fields correspond to elements of the netconfig structure. Pointers returned by network selection library routines are pointers to netconfig entries in netconfig format. See netconfig(4bnu) for more information. The netconfig(4bnu) manual page also describes the elements of the struct netconfig structure. All symbolic names, structure definitions, and constant values for the network selection feature are defined in the header files:

• /usr/include/netconfig.h

• /usr/include/sys/netconfig.h

• /usr/include/netdir.h

netconfig fields are defined as follows:

network_id

A string used to identify a transport provider. network_id consists of non-null characters and has a length of at least 1. No maximum length is specified. This name space is locally significant and the local system administrator is the naming authority responsible for ensuring that each network_id on a system is unique.

semantics

A string that identifies the semantics of the transport provider, that is, the set of services it supports, by identifying the service interface it provides. This is closely related to, but not identical with, the API with which applications are supposed to access the network. Typically, an application will specify its API by pushing an appropriate STREAMS module (such as timod) and using an appropriate user-level library (such as the Transport Layer Interface (TLI) library). The semantics field is mandatory. The following semantics are recognized:

tpi_clts

Transport Provider Interface, connectionless

tpi_cots

Transport Provider Interface, connection-oriented

tpi_cots_ord

Transport Provider Interface, connection-oriented and supports orderly release

tpi_raw

Transport Provider Interface, raw

flags

The flags field contains two-valued (true and false) attributes of transport providers. flags is a string of characters, each of which specifies the value of the corresponding attribute. If the character is present, the attribute is true. If the character is absent, the attribute is false. A dash (-) indicates no attributes are present. The characters currently recognized are:

v

Visible network. Used to establish a default list of networks to search when the environment variable NETPATH is unset. See ``The NETPATH environment variable'', for a description of how the v flag is used.

b

Enable Remote Procedure Call (RPC) broadcast. Used by rpc_broadcast (see rpc_clnt_calls(3rpc)).

protofamily

The protofamily and protoname fields are provided for protocol-specific applications. The protofamily field contains a string that identifies a protocol family. The protofamily identifier follows the rules for network_ids: it is a string of non-null characters with a length of at least 1. No maximum length is specified.

A dash (-) in the protofamily field indicates that none of the available protocol family identifiers applies, that is, the transport provider is experimental. An application that wants to have family characteristics can match on the protofamily field when selecting a network. (For example, an application can search for an OSI family.) In this case, the application is not protocol-independent, since it has searched only for OSI entries. The following are examples of protocol family identifiers:

loopback

Loopback (local to host)

inet

Internetwork: UDP, TCP, and so on

implink

ARPANET imp addresses

pup

PUP protocols: for example, BSP

chaos

MIT CHAOS protocols

ns

XEROX NS protocols

nbs

National Bureau of Standards (NBS) protocols

ecma

European Computer Manufacturers Association

datakit

Datakit protocols

ccitt

CCITT protocols, X.25, and so on.

sna

IBM SNA

decnet

DECNET

dli

Direct data link interface

lat

LAT

hylink

NSC Hyperchannel

appletalk

Apple Talk

nit

Network Interface Tap

ieee802

IEEE 802.2; also ISO 8802

osi

Umbrella for all families used by OSI

x25

CCITT X.25 in particular

osinet

AFI = 47, IDI = 4

gosip

US Government OSI

protoname

The protoname field contains a string that identifies a protocol. This field is currently used only for the inet family. For any other family, the protocol name field contains a dash (-). The protoname identifier follows the same rules as network_ids: The string consists of non-null characters and has a length of at least 1. No maximum length is specified.

The protoname field may contain:

icmp

Internet Control Message Protocol

tcp

Transmission Control Protocol

udp

User Datagram Protocol

device

The device is the full pathname of the device used to connect to the remote machine via the transport provider. Typically, this device will be in the /dev directory. The device must be specified.

nametoaddr_libs

The nametoaddr_libs support a directory service (that is, a name-to-address mapping service) for the network. This service is implemented by the name-to-address mapping feature. If a transport is not provided with such a library, that is, if the nametoaddr_libs field in the netconfig file contains only a dash, the network selection request will fail.

The nametoaddr_libs field consists of a comma-separated list of full pathnames to dynamically linked libraries.

The system administrator determines the order of the entries in the netconfig database. Because the network selection library routines that access netconfig directly return entries in order, beginning at the top of the /etc/netconfig file, the order in which networks are entered in the file by the system administrator becomes the default search path for applications choosing networks to which they will connect.

#network_id   semantics     flags  protofamily  protoname  device          nametoaddr_libs
#
ticlts        tpi_clts      v      loopback     -          /dev/ticlts     /usr/lib/straddr.so
ticots        tpi_cots      v      loopback     -          /dev/ticots     /usr/lib/straddr.so
ticotsord     tpi_cots_ord  v      loopback     -          /dev/ticotsord  /usr/lib/straddr.so
tcp           tpi_cots_ord  v      inet         tcp        /dev/tcp        /usr/lib/tcpip.so,/usr/lib/resolv.so
udp           tpi_clts      v      inet         udp        /dev/udp        /usr/lib/tcpip.so,/usr/lib/resolv.so
icmp          tpi_raw       -      inet         icmp       /dev/icmp       /usr/lib/tcpip.so,/usr/lib/resolv.so
rawip         tpi_raw       -      inet         -          /dev/rawip      /usr/lib/tcpip.so,/usr/lib/resolv.so