NS(4F)                                                                  NS(4F)



NAME
       ns - Xerox Network Systems(tm) protocol family

SYNOPSIS
       options NS
       options NSIP
       pseudo-device ns

DESCRIPTION
       The  NS  protocol  family is a collection of protocols layered atop the
       _I_n_t_e_r_n_e_t _D_a_t_a_g_r_a_m _P_r_o_t_o_c_o_l (IDP) transport layer, and using  the  Xerox
       NS  address  formats.   The NS family provides protocol support for the
       SOCK_STREAM, SOCK_DGRAM, SOCK_SEQPACKET, and SOCK_RAW socket types; the
       SOCK_RAW interface is a debugging tool, allowing you to trace all pack‐
       ets entering, (or with toggling kernel variable, additionally  leaving)
       the local host.

ADDRESSING
       NS  addresses  are  12  byte quantities, consisting of a 4 byte Network
       number, a 6 byte Host number and a 2 byte port number,  all  stored  in
       network standard format.  (on the VAX these are word and byte reversed;
       on the Sun they are  not  reversed).   The  include  file  <_n_e_t_n_s_/_n_s_._h>
       defines  the  NS  address as a structure containing unions (for quicker
       comparisons).

       Sockets in the Internet protocol family use  the  following  addressing
       structure:

       struct sockaddr_ns {
            short          sns_family;
            struct ns_addr sns_addr;
            char      sns_zero[2];
       };

       where an ns_addr is composed as follows:

       union ns_host {
            u_char         c_host[6];
            u_short        s_host[3];
       };

       union ns_net {
            u_char         c_net[4];
            u_short        s_net[2];
       };

       struct ns_addr {
            union ns_net   x_net;
            union ns_host  x_host;
            u_short   x_port;
       };

       Sockets  may be created with an address of all zeroes to effect ‘‘wild‐
       card’’ matching on incoming messages.  The local port address specified
       in  a  _b_i_n_d(2)  call  is  restricted to be greater than NSPORT_RESERVED
       (=3000, in <netns/ns.h>) unless the creating process is running as  the
       super-user, providing a space of protected port numbers.

PROTOCOLS
       The  NS  protocol family supported by the operating system is comprised
       of the Internet Datagram Protocol (IDP) _i_d_p(4P), Error Protocol (avail‐
       able through IDP), and Sequenced Packet Protocol (SPP) _s_p_p(4P).

       SPP  is used to support the SOCK_STREAM and SOCK_SEQPACKET abstraction,
       while IDP is used to support the  SOCK_DGRAM  abstraction.   The  Error
       protocol  is  responded to by the kernel to handle and report errors in
       protocol processing; it is, however, only accessible to  user  programs
       through heroic actions.

SEE ALSO
       intro(3),   byteorder(3N),  gethostbyname(3N),  getnetent(3N),  getpro‐
       toent(3N), getservent(3N), ns(3N), intro(4N), spp(4P), idp(4P), nsip(4)
       Internet Transport Protocols, Xerox Corporation document XSIS-028112
       An Advanced 4.3BSD Interprocess Communication Tutorial



4.3 Berkeley Distribution        July 30, 1985                          NS(4F)