#include <netdb.h> 

struct protoent *getprotoent()

struct protoent *getprotobyname(name)
char *name;

struct protoent *getprotobynumber(proto)
int proto;

setprotoent(stayopen)
int stayopen

endprotoent()

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

The members of this structure are:

\w'p_aliases'u+2n p_name The official name of the protocol.

\w'p_aliases'u+2n p_aliases A zero terminated list of alternate names for the protocol.

\w'p_aliases'u+2n p_proto The protocol number.

Getprotoent reads the next line of the file, opening the file if necessary.

Setprotoent opens and rewinds the file. If the stayopen flag is non-zero, the net data base will not be closed after each call to getprotobyname or getprotobynumber .

Endprotoent closes the file.

Getprotobyname and getprotobynumber sequentially search from the beginning of the file until a matching protocol name or protocol number is found, or until EOF is encountered.