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man pages section 4: File Formats

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Updated: July 2017



netconfig - network configuration database




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.


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.


Transport Provider Interface, connectionless


Transport Provider Interface, connection oriented


Transport Provider Interface, connection oriented, supports orderly release.


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:


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 (local to host).


Internetwork: UDP, TCP, and the like.


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


ARPANET imp addresses


PUP protocols: for example, BSP


MIT CHAOS protocols


XEROX NS protocols


NBS protocols


European Computer Manufacturers Association


DATAKIT protocols


CCITT protocols, X.25, and the like.






Direct data link interface




NSC Hyperchannel


Apple Talk


Network Interface Tap


IEEE 802.2; also ISO 8802


Umbrella for all families used by OSI (for example, protosw lookup)


CCITT X.25 in particular


AFI = 47, IDI = 4


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.


Transmission Control Protocol


User Datagram Protocol


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(3C).

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


unsigned long nc_flag


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:


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.



Example 1 A Sample netconfig File

Below is a sample netconfig file:

#  The "Network Configuration" File.
# Each entry is of the form:
#   <networkid> <semantics> <flags> <protofamily> <protoname> <device>
#         <nametoaddrlibs>
# The "-" in <nametoaddrlibs> for inet family transports indicates
# redirection to the name service switch policies for "hosts" and
# "services". The "-" may be replaced by nametoaddr libraries that
# comply with the SVr4 specs, in which case the name service switch
# will not be used for netdir_getbyname, netdir_getbyaddr,
# gethostbyname, gethostbyaddr, getservbyname, and getservbyport.
# There are no nametoaddr_libs for the inet family in Solaris anymore.
udp6       tpi_clts      v   inet6   udp    /dev/udp6       -
tcp6       tpi_cots_ord  v   inet6   tcp    /dev/tcp6       -
udp        tpi_clts      v   inet    udp    /dev/udp        -
tcp        tpi_cots_ord  v   inet    tcp    /dev/tcp        -
rawip      tpi_raw       -   inet    -      /dev/rawip      -
ticlts     tpi_clts      v   loopback -      /dev/ticlts     straddr.so
ticotsord  tpi_cots_ord  v   loopback -      /dev/ticotsord  straddr.so
ticots     tpi_cots      v   loopback -      /dev/ticots     straddr.so



See Also

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

Introduction to Oracle Solaris 11.3 Network Services