NS(4F) — Unix Programmer’s Manual

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 Internet Datagram Protocol (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 packets 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 <netns/ns.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 {
shortsns_family;
struct ns_addrsns_addr;
charsns_zero[2];
};
where an ns_addr is composed as follows:
union ns_host {
u_charc_host[6];
u_shorts_host[3];
};
union ns_net {
u_charc_net[4];
u_shorts_net[2];
};
struct ns_addr {
union ns_netx_net;
union ns_hostx_host;
u_shortx_port;
};

Sockets may be created with an address of all zeroes to effect “wildcard” matching on incoming messages. The local port address specified in a bind(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) idp(4P), Error Protocol (available through IDP), and Sequenced Packet Protocol (SPP) spp(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.

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