NAME

       getnetent, getnetbyname, getnetbyaddr, setnetent, endnetent - get network entry

SYNOPSIS

       #include <netdb.h>

       struct netent *getnetent(void);

       struct netent *getnetbyname(const char *name);

       struct netent *getnetbyaddr(uint32_t net, int type);

       void setnetent(int stayopen);

       void endnetent(void);

DESCRIPTION

       The  getnetent()  function reads the next entry from the networks database and returns a netent structure
       containing the broken-out fields from the entry.  A connection is opened to the database if necessary.

       The getnetbyname() function returns a netent structure for the entry from the database that  matches  the
       network name.

       The  getnetbyaddr()  function returns a netent structure for the entry from the database that matches the
       network number net of type type.  The net argument must be in host byte order.

       The setnetent() function opens a connection to the database, and sets the next entry to the first  entry.
       If  stayopen  is  nonzero, then the connection to the database will not be closed between calls to one of
       the getnet*() functions.

       The endnetent() function closes the connection to the database.

       The netent structure is defined in <netdb.h> as follows:

           struct netent {
               char      *n_name;     /* official network name */
               char     **n_aliases;  /* alias list */
               int        n_addrtype; /* net address type */
               uint32_t   n_net;      /* network number */
           }

       The members of the netent structure are:

       n_name The official name of the network.

       n_aliases
              A NULL-terminated list of alternative names for the network.

       n_addrtype
              The type of the network number; always AF_INET.

       n_net  The network number in host byte order.

RETURN VALUE

       The getnetent(), getnetbyname() and getnetbyaddr() functions return a pointer to a  statically  allocated
       netent structure, or a null pointer if an error occurs or the end of the file is reached.

FILES

       /etc/networks
              networks database file

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌───────────────┬───────────────┬───────────────────────────┐
       │Interface      │ Attribute     │ Value                     │
       ├───────────────┼───────────────┼───────────────────────────┤
       │getnetent()    │ Thread safety │ MT-Unsafe race:netent     │
       │               │               │ race:netentbuf env locale │
       ├───────────────┼───────────────┼───────────────────────────┤
       │getnetbyname() │ Thread safety │ MT-Unsafe race:netbyname  │
       │               │               │ env locale                │
       ├───────────────┼───────────────┼───────────────────────────┤
       │getnetbyaddr() │ Thread safety │ MT-Unsafe race:netbyaddr  │
       │               │               │ locale                    │
       ├───────────────┼───────────────┼───────────────────────────┤
       │setnetent(),   │ Thread safety │ MT-Unsafe race:netent env │
       │endnetent()    │               │ locale                    │
       └───────────────┴───────────────┴───────────────────────────┘
       In  the  above  table,  netent  in  race:netent  signifies  that  if  any  of  the functions setnetent(),
       getnetent(), or endnetent() are used in parallel in different threads of a program, then data races could
       occur.

CONFORMING TO

       POSIX.1-2001, POSIX.1-2008, 4.3BSD.

NOTES

       In glibc versions before 2.2, the net argument of getnetbyaddr() was of type long.

SEE ALSO

       getnetent_r(3), getprotoent(3), getservent(3)
       RFC 1101

COLOPHON

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       information  about  reporting  bugs,  and  the  latest  version  of  this   page,   can   be   found   at
       https://www.kernel.org/doc/man-pages/.