*nix Documentation Project
·  Home
 +   man pages
·  Linux HOWTOs
·  FreeBSD Tips
·  *niX Forums

  man pages->IRIX man pages -> netintro (7)              


NETINTRO(7)							   NETINTRO(7)

NAME    [Toc]    [Back]

     networking	- introduction to networking facilities

SYNOPSIS    [Toc]    [Back]

     #include <sys/socket.h>
     #include <net/route.h>
     #include <net/if.h>

DESCRIPTION    [Toc]    [Back]

     This section briefly describes the	networking facilities available	in the
     system.  Documentation in this part of section 7 is broken	up into	three
     areas:  protocol families (domains), protocols, and network interfaces.
     Entries describing	a protocol family are marked ``7F,'' while entries
     describing	protocol use are marked	``7P.''	 Hardware support for network
     interfaces	are found among	the standard ``7'' entries.

     All network protocols are associated with a specific protocol family.  A
     protocol family provides basic services to	the protocol implementation to
     allow it to function within a specific network environment.  These
     services may include packet fragmentation and reassembly, routing,
     addressing, and basic transport.  A protocol family may support multiple
     methods of	addressing, though the current protocol	implementations	do
     not.  A protocol family is	normally comprised of a	number of protocols,
     one per socket(2) type.  It is not	required that a	protocol family
     support all socket	types.	A protocol family may contain multiple
     protocols supporting the same socket abstraction.

     A protocol	supports one of	the socket abstractions	detailed in socket(2).
     A specific	protocol may be	accessed either	by creating a socket of	the
     appropriate type and protocol family, or by requesting the	protocol
     explicitly	when creating a	socket.	 Protocols normally accept only	one
     type of address format, usually determined	by the addressing structure
     inherent in the design of the protocol family/network architecture.
     Certain semantics of the basic socket abstractions	are protocol specific.
     All protocols are expected	to support the basic model for their
     particular	socket type, but may, in addition, provide non-standard
     facilities	or extensions to a mechanism.  For example, a protocol
     supporting	the SOCK_STREAM	abstraction may	allow more than	one byte of
     out-of-band data to be transmitted	per out-of-band	message.

     A network interface is similar to a device	interface.  Network interfaces
     comprise the lowest layer of the networking subsystem, interacting	with
     the actual	transport hardware.  An	interface may support one or more
     protocol families and/or address formats.	The ethernet(7)	manual entry
     lists messages which may appear on	the console and/or in the system error
     log, /var/adm/SYSLOG (see syslogd(1M)), due to errors in device

PROTOCOLS    [Toc]    [Back]

     The system	currently supports the DARPA Internet protocols.  Raw socket
     interfaces	are provided to	the IP protocol	layer of the DARPA Internet
     and to the	link-level layer.  Consult the appropriate manual pages	in

									Page 1

NETINTRO(7)							   NETINTRO(7)

     this section for more information regarding the support for each protocol

ADDRESSING    [Toc]    [Back]

     Associated	with each protocol family is an	address	format.	 The following
     address formats are used by the system (and additional formats are
     defined for possible future implementation):

     #define AF_UNIX	       1      /* local to host (pipes) */
     #define AF_INET	       2      /* internetwork: UDP, TCP, etc. */

ROUTING    [Toc]    [Back]

     The network facilities provided limited packet routing.  A	simple set of
     data structures comprise a	``routing table'' used in selecting the
     appropriate network interface when	transmitting packets.  This table
     contains a	single entry for each route to a specific network or host.  A
     user process, the routing daemon, maintains this data base	with the aid
     of	two socket-specific ioctl(2) commands, SIOCADDRT and SIOCDELRT.	 The
     commands allow the	addition and deletion of a single routing table	entry,
     respectively.  Routing table manipulations	may only be carried out	by

     A routing table entry has the following form, as defined in

     struct rtentry {
	    u_long    rt_hash;
	    struct    sockaddr rt_dst;
	    struct    sockaddr rt_gateway;
	    short     rt_flags;
	    short     rt_refcnt;
	    u_long    rt_use;
	    struct    ifnet *rt_ifp;

     with rt_flags defined from,

     #define RTF_UP	       0x1    /* route usable */
     #define RTF_GATEWAY       0x2    /* destination is	a gateway */
     #define RTF_HOST	       0x4    /* host entry (net otherwise) */
     #define RTF_DYNAMIC       0x10   /* created dynamically (by redirect) */
     #define RTF_MODIFIED      0x10   /* modified dynamically (by redirect) */

     Routing table entries come	in three flavors: for a	specific host, for all
     hosts on a	specific network, for any destination not matched by entries
     of	the first two types (a wildcard	route).	When the system	is booted and
     addresses are assigned to the network interfaces, each protocol family
     installs a	routing	table entry for	each interface when it is ready	for
     traffic.  Normally	the protocol specifies the route through each
     interface as a ``direct'' connection to the destination host or network.
     If	the route is direct, the transport layer of a protocol family usually
     requests the packet be sent to the	same host specified in the packet.

									Page 2

NETINTRO(7)							   NETINTRO(7)

     Otherwise,	the interface is requested to address the packet to the
     gateway listed in the routing entry (i.e.,	the packet is forwarded).

     Routing table entries installed by	a user process may not specify the
     hash, reference count, use, or interface fields; these are	filled in by
     the routing routines.  If a route is in use when it is deleted (rt_refcnt
     is	non-zero), the routing entry will be marked down and removed from the
     routing table, but	the resources associated with it will not be reclaimed
     until all references to it	are released. The routing code returns EEXIST
     if	requested to duplicate an existing entry, ESRCH	if requested to	delete
     a non-existent entry, or ENOBUFS if insufficient resources	were available
     to	install	a new route.  User processes read the routing tables through
     the /dev/kmem device.  The	rt_use field contains the number of packets
     sent along	the route.

     When routing a packet, the	kernel will first attempt to find a route to
     the destination host.  Failing that, a search is made for a route to the
     network of	the destination.  Finally, any route to	a default
     (``wildcard'') gateway is chosen.	If multiple routes are present in the
     table, the	first route found will be used.	 If no entry is	found, the
     destination is declared to	be unreachable.

     A wildcard	routing	entry is specified with	a zero destination address
     value.  Wildcard routes are used only when	the system fails to find a
     route to the destination host and network.	 The combination of wildcard
     routes and	routing	redirects can provide an economical mechanism for
     routing traffic.

INTERFACES    [Toc]    [Back]

     Each network interface in a system	corresponds to a path through which
     messages may be sent and received.	 A network interface usually has a
     hardware device associated	with it, though	certain	interfaces such	as the
     loopback interface, lo(7),	do not.

     The following ioctl calls may be used to manipulate network interfaces.
     The ioctl is made on a socket (typically of type SOCK_DGRAM) in the
     desired domain.  Unless specified otherwise, the request takes an
     ifrequest structure as its	parameter.  This structure has the form

     struct    ifreq {
     #define   IFNAMSIZ	 16
	  char ifr_name[IFNAMSIZE];	     /*	if name, e.g. "enp0" */
	  union	{
	       struct	 sockaddr ifru_addr;
	       struct	 sockaddr ifru_dstaddr;
	       struct	 sockaddr ifru_broadaddr;
	       short	 ifru_flags;
	       int  ifru_metric;
	       caddr_t	 ifru_data;
	  } ifr_ifru;
     #define   ifr_addr	      ifr_ifru.ifru_addr       /* address */
     #define   ifr_dstaddr    ifr_ifru.ifru_dstaddr    /* other	end of p-to-p link */

									Page 3

NETINTRO(7)							   NETINTRO(7)

     #define   ifr_broadaddr  ifr_ifru.ifru_broadaddr  /* broadcast address */
     #define   ifr_flags      ifr_ifru.ifru_flags      /* flags	*/
     #define   ifr_metric     ifr_ifru.ifru_metric	    /* metric */
     #define   ifr_data	      ifr_ifru.ifru_data       /* for use by interface */

	  Set interface	address	for protocol family.  Following	the address
	  assignment, the ``initialization'' routine for the interface is

	  Get interface	address	for protocol family.

	  Set point to point address for protocol family and interface.

	  Get point to point address for protocol family and interface.

	  Set broadcast	address	for protocol family and	interface.

	  Get broadcast	address	for protocol family and	interface.

	  Set interface	flags field.  If the interface is marked down, any
	  processes currently routing packets through the interface are
	  notified; some interfaces may	be reset so that incoming packets are
	  no longer received.  When marked up again, the interface is

	  Get interface	flags.

	  Set interface	routing	metric.	 The metric is used only by user-level

	  Get interface	metric.

	  Get interface	configuration list.  This request takes	an ifconf
	  structure (see below)	as a value-result parameter.  The ifc_len
	  field	should be initially set	to the size of the buffer pointed to
	  by ifc_buf.  On return it will contain the length, in	bytes, of the
	  configuration	list.

									Page 4

NETINTRO(7)							   NETINTRO(7)

      *	Structure used in SIOCGIFCONF request.
      *	Used to	retrieve interface configuration
      *	for machine (useful for	programs which
      *	must know all networks accessible).
     struct    ifconf {
	  int  ifc_len;	      /* size of associated buffer */
	  union	{
	       caddr_t	 ifcu_buf;
	       struct	 ifreq *ifcu_req;
	  } ifc_ifcu;
     #define   ifc_buf	 ifc_ifcu.ifcu_buf   /*	buffer address */
     #define   ifc_req	 ifc_ifcu.ifcu_req   /*	array of structures returned */

SEE ALSO    [Toc]    [Back]

     socket(2),	ioctl(2), routed(1M), route(7F), IRIX Network Programming

									PPPPaaaaggggeeee 5555
[ Back ]
 Similar pages
Name OS Title
networking Tru64 Introduction to socket networking facilities
netintro Tru64 Introduction to socket networking facilities
audio IRIX Introduction to audio facilities
realtime IRIX introduction to realtime and scheduler facilities
intro IRIX introduction to SVR4 networking functions and libraries
DtMrm HP-UX initializing widgets for URM facilities
sigvec OpenBSD software signal facilities
sigvector HP-UX software signal facilities
sigvec FreeBSD software signal facilities
sigvec NetBSD software signal facilities
Copyright © 2004-2005 DeniX Solutions SRL
newsletter delivery service