Protocol Names – protoent

The protoent structure defines the protocol-name mapping used with getprotobyname(), getprotobynumber(), and getprotoent() and are defined in getprotoent():

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

For more information, see the getprotobyname(3C), getprotobynumber(3C), and getprotoent(3C) man pages.