NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | FILES | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

GETNETENT(3)              Linux Programmer's Manual             GETNETENT(3)

NAME         top

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

SYNOPSIS         top

       #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         top

       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         top

       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         top

       /etc/networks
              networks database file

ATTRIBUTES         top

       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         top

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

NOTES         top

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

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 4.08 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

GNU                              2016-10-08                     GETNETENT(3)