The network configuration database, /etc/netconfig, is a system file used to store information about networks that are connected to the system. The netconfig database and the routines that access it (see getnetconfig(3NSL)) are part of the Network Selection component. The Network Selection component also includes getnetpath(3NSL) routines to provide application-specific network search paths. These routines access the netconfig database based on the environment variable NETPATH. See environ(5).

netconfig contains an entry for each network available on the system. Entries are separated by newlines. Fields are separated by whitespace and occur in the order in which they are described below. Whitespace can be embedded as ``\blank'' or ``\tab''. Backslashes may be embedded as ``\\''. Lines in /etc/netconfig that begin with a # (hash) in column 1 are treated as comments.

Each of the valid lines in the netconfig database correspond to an available transport. Each entry is of the form:

network ID semantics flag protocol-family protocol-name \ network-device translation-libraries

network ID

A string used to uniquely identify a network. network ID consists of non-null characters, and has a length of at least 1. No maximum length is specified. This namespace is locally significant and the local system administrator is the naming authority. All network IDs on a system must be unique.

semantics

The semantics field is a string identifying the ``semantics'' of the network, that is, the set of services it supports, by identifying the service interface it provides. 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, supports orderly release.

flag

The flag field records certain two-valued (``true'' and ``false'') attributes of networks. flag is a string composed of a combination of characters, each of which indicates the value of the corresponding attribute. If the character is present, the attribute is ``true.'' If the character is absent, the attribute is ``false.'' ``-'' indicates that none of the attributes are present. Only one character is currently recognized:

v

Visible (``default'') network. Used when the environment variable NETPATH is unset.

protocol family

The protocol family and protocol name fields are provided for protocol-specific applications. The protocol family field contains a string that identifies a protocol family. The protocol family identifier follows the same rules as those for network IDs; the string consists of non-null characters, it has a length of at least 1, and there is no maximum length specified. A ``-'' in the protocol family field indicates that no protocol family identifier applies (the network is experimental). The following are examples:

loopback

Loopback (local to host).

inet

Internetwork: UDP, TCP, and the like.

inet6

Internetwork over IPv6: UDP, TCP, and the like.

implink

ARPANET imp addresses

pup

PUP protocols: for example, BSP

chaos

MIT CHAOS protocols

ns

XEROX NS protocols

nbs

NBS protocols

ecma

European Computer Manufacturers Association

datakit

DATAKIT protocols

ccitt

CCITT protocols, X.25, and the like.

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 (for example, protosw lookup)

x25

CCITT X.25 in particular

osinet

AFI = 47, IDI = 4

gosip

U.S. Government OSI

protocol name

The protocol name field contains a string that identifies a protocol. The protocol name identifier follows the same rules as those for network IDs; that is, the string consists of non-NULL characters, it has a length of at least 1, and there is no maximum length specified. A ``-'' indicates that none of the names listed apply. The following protocol names are recognized.

tcp

Transmission Control Protocol

udp

User Datagram Protocol

icmp

Internet Control Message Protocol

network device

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

translation libraries

The name-to-address translation libraries support a ``directory service'' (a name-to-address mapping service) for the network. A ``-'' in this field indicates the absence of any translation libraries. This has a special meaning for networks of the protocol family inet : its name-to-address mapping is provided by the name service switch based on the entries for hosts and services in nsswitch.conf(4). For networks of other families, a ``-'' indicates non-functional name-to-address mapping. Otherwise, this field consists of a comma-separated list of pathnames to dynamically linked libraries. The pathname of the library can be either absolute or relative. See dlopen(3DL).

Each field corresponds to an element in the struct netconfig structure. struct netconfig and the identifiers described on this manual page are defined in <netconfig.h>. This structure includes the following members:

char *nc_netid

Network ID, including NULL terminator.

unsigned long nc_semantics

Semantics.

unsigned long nc_flag

Flags.

char *nc_protofmly

Protocol family.

char *nc_proto

Protocol name.

char *nc_device

Full pathname of the network device.

unsigned long nc_nlookups

Number of directory lookup libraries.

char **nc_lookups

Names of the name-to-address translation libraries.

unsigned long nc_unused[9]

Reserved for future expansion.

The nc_semantics field takes the following values, corresponding to the semantics identified above:

NC_TPI_CLTS

NC_TPI_COTS

NC_TPI_COTS_ORD

NC_VISIBLE

<netconfig.h>

dlopen(3DL), getnetconfig(3NSL), getnetpath(3NSL), nsswitch.conf(4)

System Administration Guide: IP Services