netdb(5)                                                           netdb(5)

NAME
     netdb - definitions for network database operations

SYNOPSIS
     #include <netdb.h>

DESCRIPTION
     The <netdb.h> header defines the type inportt and the type inaddrt
     as defined in <netinet/in.h>.

     The <netdb.h> header defines the hostent structure that includes at
     least the following members:

     char  *hname       Official name of the host

     char **haliases    A pointer to an array of pointers to alternative
                         host names, terminated by a null pointer.

     int    haddrtype   Address type.

     int    hlength     The length, in bytes, of the address.

     char **haddrlist  A pointer to an array of pointers to network
                         addresses (in network byte order) for the host,
                         terminated by a null pointer.

     The <netdb.h> header defines the netent structure that includes at
     least the following members:

     char  *nname       Official, fully-qualified (including the domain)
                         name of the host.

     char **naliases    A pointer to an array of pointers to alternative
                         network names, terminated by a null pointer.

     int    naddrtype   The address type of the network.

     inaddrt nnet     The network number, in host byte order.

     The <netdb.h> header defines the protoent structure that includes at
     least the following members:

     char  *pname       Official name of the protocol.

     char **paliases    A pointer to an array of pointers to alternative
                         protocol names, terminated by a null pointer.

     int    pproto      The protocol number.







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netdb(5)                                                           netdb(5)

     The <netdb.h> header defines the servent structure that includes at
     least the following members:

     char  *sname       Official name of the service.

     char **saliases    A pointer to an array of pointers to alternative
                         service names, terminated by a null pointer.

     int    sport       The port number at which the service resides, in
                         network byte order.

     char  *sproto      The name of the protocol to use when contacting
                         the service.

     The <netdb.h> header defines the macro IPPORTRESERVED with the value
     of the highest reserved Internet port number.

     The <netdb.h> header provides a declaration for herrno:

     extern int herrno;

     The <netdb.h> header defines the following macros for use as error
     values for gethostbyaddr and gethostbyname:

     HOSTNOTFOUND

     NODATA

     NORECOVERY

     TRYAGAIN























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netdb(5)                                                           netdb(5)

     The following are declared as functions, and may also be defined as
     macros:

     void             endhostent(void);
     void             endnetent(void);
     void             endprotoent(void);
     void             endservent(void);
     struct hostent  *gethostbyaddr(const void *addr, sizet len, int type);
     struct hostent  *gethostbyname(const char *name);
     struct hostent  *gethostent(void);
     struct netent   *getnetbyaddr(inaddrt net, int type);
     struct netent   *getnetbyname(const char *name);
     struct netent   *getnetent(void);
     struct protoent *getprotobyname(const char *name);
     struct protoent *getprotobynumber(int proto);
     struct protoent *getprotoent(void);
     struct servent  *getservbyname(const char *name, const char *proto);
     struct servent  *getservbyport(int port, const char *proto);
     struct servent  *getservent(void);
     void             sethostent(int stayopen);
     void             setnetent(int stayopen);
     void             setprotoent(int stayopen);
     void             setservent(int stayopen)

     Inclusion of the <netdb.h> header may also make visible all symbols
     from <netinet/in.h>.

SEE ALSO
     gethostent(3N-xs), getnetent(3N-xs), getprotoent(3N-xs),
     getservent(3N-xs).
























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