usr/include/netdb.h

/*      netdb.h 4.1     82/10/05        */
/*
 * Structures returned by network
 * data base library.  All addresses
 * are supplied in host order, and
 * returned in network order (suitable
 * for use in system calls).
 */
struct  hostent {
        char    *h_name;        /* official name of host */
        char    **h_aliases;    /* alias list */
        int     h_addrtype;     /* host address type */
        int     h_length;       /* length of address */
        char    *h_addr;        /* address */
};

/*
 * Assumption here is that a network number
 * fits in 32 bits -- probably a poor one.
 */
struct  netent {
        char    *n_name;        /* official name of net */
        char    **n_aliases;    /* alias list */
        int     n_addrtype;     /* net address type */
        int     n_net;          /* network # */
};

struct  servent {
        char    *s_name;        /* official service name */
        char    **s_aliases;    /* alias list */
        int     s_port;         /* port # */
        char    *s_proto;       /* protocol to use */
};

struct  protoent {
        char    *p_name;        /* official protocol name */
        char    **p_aliases;    /* alias list */
        int     p_proto;        /* protocol # */
};

struct hostent  *gethostbyname(), *gethostbyaddr(), *gethostent();
struct netent   *getnetbyname(), *getnetbyaddr(), *getnetent();
struct servent  *getservbyname(), *getservbyport(), *getservent();
struct protoent *getprotobyname(), *getprotobynumber(), *getprotoent();