Return to netintro.4 CVS log

Up to [CSRG BSD Unix] / 43BSDTahoe / man / man4

Annotation of 43BSDTahoe/man/man4/netintro.4, revision 1.1

1.1     ! root        1: .\" Copyright (c) 1983 Regents of the University of California.
        !             2: .\" All rights reserved.  The Berkeley software License Agreement
        !             3: .\" specifies the terms and conditions for redistribution.
        !             4: .\"
        !             5: .\"    @(#)netintro.4  6.5 (Berkeley) 8/1/87
        !             6: .\"
        !             7: .TH NETINTRO 4 "August 1, 1987"
        !             8: .UC 5
        !             9: .SH NAME
        !            10: networking \- introduction to networking facilities
        !            11: .SH SYNOPSIS
        !            12: .nf
        !            13: .ft B
        !            14: #include <sys/socket.h>
        !            15: #include <net/route.h>
        !            16: #include <net/if.h>
        !            17: .fi R
        !            18: .fi
        !            19: .SH DESCRIPTION
        !            20: .de _d
        !            21: .if t .ta .6i 2.1i 2.6i
        !            22: .\" 2.94 went to 2.6, 3.64 to 3.30
        !            23: .if n .ta .84i 2.6i 3.30i
        !            24: ..
        !            25: .de _f
        !            26: .if t .ta .5i 1.25i 2.5i
        !            27: .\" 3.5i went to 3.8i
        !            28: .if n .ta .7i 1.75i 3.8i
        !            29: ..
        !            30: This section briefly describes the networking facilities
        !            31: available in the system.
        !            32: Documentation in this part of section
        !            33: 4 is broken up into three areas:
        !            34: .I "protocol families
        !            35: (domains),
        !            36: .IR protocols ,
        !            37: and
        !            38: .IR "network interfaces" .
        !            39: Entries describing a protocol family are marked ``4F,''
        !            40: while entries describing protocol use are marked ``4P.''
        !            41: Hardware support for network interfaces are found
        !            42: among the standard ``4'' entries.
        !            43: .PP
        !            44: All network protocols are associated with a specific
        !            45: .IR "protocol family" .
        !            46: A protocol family provides basic services to the protocol
        !            47: implementation to allow it to function within a specific
        !            48: network environment.  These services may include 
        !            49: packet fragmentation and reassembly, routing, addressing, and 
        !            50: basic transport.  A protocol family may support multiple
        !            51: methods of addressing, though the current protocol implementations
        !            52: do not.  A protocol family is normally comprised of a number
        !            53: of protocols, one per
        !            54: .IR socket (2)
        !            55: type.  It is not required that a protocol family support
        !            56: all socket types.  A protocol family may contain multiple
        !            57: protocols supporting the same socket abstraction. 
        !            58: .PP
        !            59: A protocol supports one of the socket abstractions detailed
        !            60: in
        !            61: .IR socket (2).
        !            62: A specific protocol may be accessed either by creating a
        !            63: socket of the appropriate type and protocol family, or
        !            64: by requesting the protocol explicitly when creating a socket.
        !            65: Protocols normally accept only one type of address format,
        !            66: usually determined by the addressing structure inherent in
        !            67: the design of the protocol family/network architecture.
        !            68: Certain semantics of the basic socket abstractions are
        !            69: protocol specific.  All protocols are expected to support
        !            70: the basic model for their particular socket type, but may,
        !            71: in addition, provide non-standard facilities or extensions
        !            72: to a mechanism.  For example, a protocol supporting the
        !            73: SOCK_STREAM
        !            74: abstraction may allow more than one byte of out-of-band
        !            75: data to be transmitted per out-of-band message.
        !            76: .PP
        !            77: A network interface is similar to a device interface.
        !            78: Network interfaces comprise the lowest layer of the
        !            79: networking subsystem, interacting with the actual transport
        !            80: hardware.  An interface may support one or more protocol
        !            81: families and/or address formats.
        !            82: The SYNOPSIS section of each network interface
        !            83: entry gives a sample specification
        !            84: of the related drivers for use in providing
        !            85: a system description to the
        !            86: .IR config (8)
        !            87: program.
        !            88: The DIAGNOSTICS section lists messages which may appear on the console
        !            89: and/or in the system error log,
        !            90: .I /usr/adm/messages
        !            91: (see
        !            92: .IR syslogd (8)),
        !            93: due to errors in device operation.
        !            94: .SH PROTOCOLS
        !            95: The system currently supports the DARPA Internet
        !            96: protocols and the Xerox Network Systems(tm) protocols.
        !            97: Raw socket interfaces are provided to the IP protocol
        !            98: layer of the DARPA Internet, to the IMP link layer (1822), and to
        !            99: the IDP protocol of Xerox NS.
        !           100: Consult the appropriate manual pages in this section for more
        !           101: information regarding the support for each protocol family.
        !           102: .SH ADDRESSING
        !           103: Associated with each protocol family is an address
        !           104: format.  The following address formats are used by the system (and additional
        !           105: formats are defined for possible future implementation):
        !           106: .sp 1
        !           107: .nf
        !           108: ._d
        !           109: #define        AF_UNIX 1       /* local to host (pipes, portals) */
        !           110: #define        AF_INET 2       /* internetwork: UDP, TCP, etc. */
        !           111: #define        AF_IMPLINK      3       /* arpanet imp addresses */
        !           112: #define        AF_PUP  4       /* pup protocols: e.g. BSP */
        !           113: #define        AF_NS   6       /* Xerox NS protocols */
        !           114: #define        AF_HYLINK       15      /* NSC Hyperchannel */
        !           115: .fi
        !           116: .SH ROUTING
        !           117: The network facilities provided limited packet routing.
        !           118: A simple set of data structures comprise a ``routing table''
        !           119: used in selecting the appropriate network interface when
        !           120: transmitting packets.  This table contains a single entry for
        !           121: each route to a specific network or host.  A user process,
        !           122: the routing daemon, maintains this data base with the aid
        !           123: of two socket-specific 
        !           124: .IR ioctl (2)
        !           125: commands, SIOCADDRT and SIOCDELRT.  The commands allow
        !           126: the addition and deletion of a single routing
        !           127: table entry, respectively.  Routing table manipulations may
        !           128: only be carried out by super-user.
        !           129: .PP
        !           130: A routing table entry has the following form, as defined
        !           131: in
        !           132: .RI < net/route.h >;
        !           133: .sp 1
        !           134: ._f
        !           135: .nf
        !           136: struct rtentry {
        !           137:        u_long  rt_hash;
        !           138:        struct  sockaddr rt_dst;
        !           139:        struct  sockaddr rt_gateway;
        !           140:        short   rt_flags;
        !           141:        short   rt_refcnt;
        !           142:        u_long  rt_use;
        !           143:        struct  ifnet *rt_ifp;
        !           144: };
        !           145: .sp 1
        !           146: .fi
        !           147: with
        !           148: .I rt_flags
        !           149: defined from,
        !           150: .sp 1
        !           151: .nf
        !           152: ._d
        !           153: #define        RTF_UP  0x1             /* route usable */
        !           154: #define        RTF_GATEWAY     0x2             /* destination is a gateway */
        !           155: #define        RTF_HOST        0x4             /* host entry (net otherwise) */
        !           156: #define        RTF_DYNAMIC     0x10            /* created dynamically (by redirect) */
        !           157: .fi
        !           158: .PP
        !           159: Routing table entries come in three flavors: for a specific
        !           160: host, for all hosts on a specific network, for any destination
        !           161: not matched by entries of the first two types (a wildcard route). 
        !           162: When the system is booted and addresses are assigned
        !           163: to the network interfaces, each protocol family
        !           164: installs a routing table entry for each interface when it is ready for traffic.
        !           165: Normally the protocol specifies the route
        !           166: through each interface as a ``direct'' connection to the destination host
        !           167: or network.  If the route is direct, the transport layer of
        !           168: a protocol family usually requests the packet be sent to the
        !           169: same host specified in the packet.  Otherwise, the interface
        !           170: is requested to address the packet to the gateway listed in the routing entry
        !           171: (i.e. the packet is forwarded).
        !           172: .PP
        !           173: Routing table entries installed by a user process may not specify
        !           174: the hash, reference count, use, or interface fields; these are filled
        !           175: in by the routing routines.  If
        !           176: a route is in use when it is deleted
        !           177: .RI ( rt_refcnt
        !           178: is non-zero),
        !           179: the routing entry will be marked down and removed from the routing table,
        !           180: but the resources associated with it will not
        !           181: be reclaimed until all references to it are released. 
        !           182: The routing code returns EEXIST if
        !           183: requested to duplicate an existing entry, ESRCH if
        !           184: requested to delete a non-existent entry,
        !           185: or ENOBUFS if insufficient resources were available
        !           186: to install a new route.
        !           187: User processes read the routing tables through the
        !           188: .I /dev/kmem 
        !           189: device.
        !           190: The
        !           191: .I rt_use
        !           192: field contains the number of packets sent along the route.
        !           193: .PP
        !           194: When routing a packet,
        !           195: the kernel will first attempt to find a route to the destination host.
        !           196: Failing that, a search is made for a route to the network of the destination.
        !           197: Finally, any route to a default (``wildcard'') gateway is chosen.
        !           198: If multiple routes are present in the table,
        !           199: the first route found will be used.
        !           200: If no entry is found, the destination is declared to be unreachable.
        !           201: .PP
        !           202: A wildcard routing entry is specified with a zero
        !           203: destination address value.  Wildcard routes are used
        !           204: only when the system fails to find a route to the
        !           205: destination host and network.  The combination of wildcard
        !           206: routes and routing redirects can provide an economical
        !           207: mechanism for routing traffic.
        !           208: .SH INTERFACES
        !           209: Each network interface in a system corresponds to a
        !           210: path through which messages may be sent and received.  A network
        !           211: interface usually has a hardware device associated with it, though
        !           212: certain interfaces such as the loopback interface,
        !           213: .IR lo (4),
        !           214: do not.
        !           215: .PP
        !           216: The following 
        !           217: .I ioctl
        !           218: calls may be used to manipulate network interfaces.
        !           219: The
        !           220: .I ioctl
        !           221: is made on a socket (typically of type SOCK_DGRAM)
        !           222: in the desired domain.
        !           223: Unless specified otherwise, the request takes an
        !           224: .I ifrequest
        !           225: structure as its parameter.  This structure has the form
        !           226: .PP
        !           227: .nf
        !           228: .DT
        !           229: struct ifreq {
        !           230: #define        IFNAMSIZ        16
        !           231:        char    ifr_name[IFNAMSIZE];            /* if name, e.g. "en0" */
        !           232:        union {
        !           233:                struct  sockaddr ifru_addr;
        !           234:                struct  sockaddr ifru_dstaddr;
        !           235:                struct  sockaddr ifru_broadaddr;
        !           236:                short   ifru_flags;
        !           237:                int     ifru_metric;
        !           238:                caddr_t ifru_data;
        !           239:        } ifr_ifru;
        !           240: #define        ifr_addr        ifr_ifru.ifru_addr      /* address */
        !           241: #define        ifr_dstaddr     ifr_ifru.ifru_dstaddr   /* other end of p-to-p link */
        !           242: #define        ifr_broadaddr   ifr_ifru.ifru_broadaddr /* broadcast address */
        !           243: #define        ifr_flags       ifr_ifru.ifru_flags     /* flags */
        !           244: #define        ifr_metric      ifr_ifru.ifru_metric    /* metric */
        !           245: #define        ifr_data        ifr_ifru.ifru_data      /* for use by interface */
        !           246: };
        !           247: .fi
        !           248: .TP
        !           249: SIOCSIFADDR
        !           250: Set interface address for protocol family.  Following the address
        !           251: assignment, the ``initialization'' routine for
        !           252: the interface is called.
        !           253: .TP
        !           254: SIOCGIFADDR
        !           255: Get interface address for protocol family.
        !           256: .TP
        !           257: SIOCSIFDSTADDR
        !           258: Set point to point address for protocol family and interface.
        !           259: .TP
        !           260: SIOCGIFDSTADDR
        !           261: Get point to point address for protocol family and interface.
        !           262: .TP
        !           263: SIOCSIFBRDADDR
        !           264: Set broadcast address for protocol family and interface.
        !           265: .TP
        !           266: SIOCGIFBRDADDR
        !           267: Get broadcast address for protocol family and interface.
        !           268: .TP
        !           269: SIOCSIFFLAGS
        !           270: Set interface flags field.  If the interface is marked down,
        !           271: any processes currently routing packets through the interface
        !           272: are notified;
        !           273: some interfaces may be reset so that incoming packets are no longer received.
        !           274: When marked up again, the interface is reinitialized.
        !           275: .TP
        !           276: SIOCGIFFLAGS
        !           277: Get interface flags.
        !           278: .TP
        !           279: SIOCSIFMETRIC
        !           280: Set interface routing metric.
        !           281: The metric is used only by user-level routers.
        !           282: .TP
        !           283: SIOCGIFMETRIC
        !           284: Get interface metric.
        !           285: .TP
        !           286: SIOCGIFCONF
        !           287: Get interface configuration list.  This request takes an
        !           288: .I ifconf
        !           289: structure (see below) as a value-result parameter.  The 
        !           290: .I ifc_len
        !           291: field should be initially set to the size of the buffer
        !           292: pointed to by 
        !           293: .IR ifc_buf .
        !           294: On return it will contain the length, in bytes, of the
        !           295: configuration list.
        !           296: .PP
        !           297: .nf
        !           298: .DT
        !           299: /*
        !           300:  * Structure used in SIOCGIFCONF request.
        !           301:  * Used to retrieve interface configuration
        !           302:  * for machine (useful for programs which
        !           303:  * must know all networks accessible).
        !           304:  */
        !           305: struct ifconf {
        !           306:        int     ifc_len;                /* size of associated buffer */
        !           307:        union {
        !           308:                caddr_t ifcu_buf;
        !           309:                struct  ifreq *ifcu_req;
        !           310:        } ifc_ifcu;
        !           311: #define        ifc_buf ifc_ifcu.ifcu_buf       /* buffer address */
        !           312: #define        ifc_req ifc_ifcu.ifcu_req       /* array of structures returned */
        !           313: };
        !           314: .fi
        !           315: .SH SEE ALSO
        !           316: socket(2), ioctl(2), intro(4), config(8), routed(8C)

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.