NAME

netconfig - network configuration database

SYNOPSIS

#include <netconfig.h>

DESCRIPTION

The network configuration database, /etc/netconfig, is a system file used to store information about networks connected to the system and available for use. The netconfig database and the routines that access it [see getnetconfig(3N)] are part of the UNIX System V Network Selection component. The Network Selection component also includes the environment variable NETPATH and a group of routines that access the netconfig database using NETPATH components as links to the netconfig entries. NETPATH is described in sh(1); the NETPATH access routines are discussed in getnetpath(3N). 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 ``\\''. Each field corresponds to an element in the struct netconfig structure. struct netconfig and the identifiers described on this manual page are defined in /usr/include/netconfig.h.

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 identifing the ``semantics'' of the network, i.e., 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,  connec-
            tionless

tpi_cots    Transport Provider Interface,  connec-
            tion 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 is 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, 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 ``-'' in the protocol family field indicates that no protocol family identifier applies, that is, the network is experimental. The following are examples:

          loopback    Loopback (local to host).
          inet        Internetwork: UDP, TCP, etc.
          implink     ARPANET imp addresses
          pup         PUP protocols: e.g. BSP
          chaos       MIT CHAOS protocols
          ns          XEROX NS protocols
          nbs         NBS protocols
          ecma        European Computer Manufacturers  Asso-
                      ciation
          datakit     DATAKIT protocols
          ccitt       CCITT protocols, X.25, etc.
          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
                      (e.g., 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. The following protocol names are recognized. A ``-'' indicates that none of the names listed applies.

          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.

directory lookup libraries

The directory lookup libraries support a ``directory service'' (a name-to-address mapping service) for the network. This service is implemented by the UNIX System V Name-to-Address Mapping feature. If a network is not provided with such a library, the netdir feature will not work. A ``-'' in this field indicates the absence of any lookup libraries, in which case name-to-address mapping for the network is nonfunctional. The directory lookup library field consists of a comma-separated list of full pathnames to dynamically linked libraries. Commas may be embedded as ``\,''; backslashs as ``\\''. Lines in /etc/netconfig that begin with a sharp sign (#) in column 1 are treated as comments. The struct netconfig structure includes the following members corresponding to the fields in in the netconfig database entries:

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 Full pathnames of the directory lookup libraries themselves

unsigned long nc_unused[9]       Reserved for future  expan-
                                 sion   (not  advertised  to
                                 user       level)       The
                                 nc_semantics   field  takes
                                 the    following    values,
                                 corresponding to the seman-
                                 tics identified above:
      NC_TPI_CLTS
      NC_TPI_COTS
      NC_TPI_COTS_ORD
The  nc_flag  field  is  a  bitfield.   The  following  bit,
corresponding   to   the   attribute  identified  above,  is
currently recognized. NC_NOFLAG indicates the absence of any
attributes.
      NC_VISIBLE

SEE ALSO

netdir_getbyname(3N),   getnetconfig(3N),    getnetpath(3N),
netconfig(4)
Network Programmer's Guide
System Administrator's Guide

FILES

/etc/netconfig
/usr/include/netconfig.h