The netconfig file defines a list of "transport names", describing their semantics and protocol. In this file is only used by the RPC library code.

Entries have the following format:

network_id semantics flags family protoname device libraries

Entries consist of the following fields:

• network_id The name of the transport described.
• semantics Describes the semantics of the transport. This can be one of:
  • tpi_clts Connectionless transport.
  • tpi_cots Connection-oriented transport
  • tpi_cots_ord Connection-oriented, ordered transport.
  • tpi_raw A raw connection.
• flags This field is either blank (specified by "-"), or contains one or more of the following characters:
  • b The network represented by this entry is broadcast capable. This flag is meaningless in
  • v The entry may be returned by the getnetpath(3) function.
• family The protocol family of the transport. This is currently one of:
  • inet6 The IPv6 (PF_INET6) family of protocols.
  • inet The IPv4 (PF_INET) family of protocols.
  • loopback The PF_LOCAL protocol family.
• protoname The name of the protocol used for this transport. Can currently be either udp, tcp or empty.
• device This field is always empty in
• libraries This field is always empty in

The order of entries in this file will determine which transport will be preferred by the RPC library code, given a match on a specified network type. For example, if a sample network config file would look like this:

udp6       tpi_clts      v     inet6    udp     -       -
tcp6       tpi_cots_ord  v     inet6    tcp     -       -
udp        tpi_clts      v     inet     udp     -       -
tcp        tpi_cots_ord  v     inet     tcp     -       -
rawip      tpi_raw       -     inet      -      -       -
local      tpi_cots_ord  -     loopback  -      -       -

then using the network type udp in calls to the RPC library function (see rpc(3)) will make the code first try udp6, and then udp.

getnetconfig(3) and associated functions will parse this file and return structures of the following format:

struct netconfig {
    char *nc_netid;              /* Network ID */
    unsigned long nc_semantics;  /* Semantics */
    unsigned long nc_flag;       /* Flags */
    char *nc_protofmly;          /* Protocol family */
    char *nc_proto;              /* Protocol name */
    char *nc_device;             /* Network device pathname (unused) */
    unsigned long nc_nlookups;   /* Number of lookup libs (unused) */
    char **nc_lookups;           /* Names of the libraries (unused) */
    unsigned long nc_unused[9];  /* reserved */
};

• /etc/netconfig

getnetconfig(3), getnetpath(3)