A zero terminated list of alternate names for the protocol.
p_proto
The protocol number.
The getprotoent function reads the next line of the file, opening the file if necessary.
The setprotoent function 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.
The endprotoent function closes the file.
The getprotobyname function 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.
