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diff --git a/man7/ipv6.7 b/man7/ipv6.7 new file mode 100644 index 000000000..b2655a457 --- /dev/null +++ b/man7/ipv6.7 @@ -0,0 +1,266 @@ +.\" This man page is Copyright (C) 2000 Andi Kleen <ak@muc.de>. +.\" Permission is granted to distribute possibly modified copies +.\" of this page provided the header is included verbatim, +.\" and in case of nontrivial modification author and date +.\" of the modification is added to the header. +.\" $Id: ipv6.7,v 1.3 2000/12/20 18:10:31 ak Exp $ +.TH IPV6 7 1999-06-29 "Linux Man Page" "Linux Programmer's Manual" +.SH NAME +ipv6, PF_INET6 \- Linux IPv6 protocol implementation +.SH SYNOPSIS +.B #include <sys/socket.h> +.br +.B #include <netinet/in.h> +.sp +.sp +.IB tcp6_socket " = socket(PF_INET6, SOCK_STREAM, 0);" +.br +.IB raw6_socket " = socket(PF_INET6, SOCK_RAW, " protocol ");" +.br +.IB udp6_socket " = socket(PF_INET6, SOCK_DGRAM, " protocol ");" +.SH DESCRIPTION +Linux 2.2 optionally implements the Internet Protocol, version 6. +This man page contains a description of the IPv6 basic API as +implemented by the Linux kernel and glibc 2.1. The interface +is based on the BSD sockets interface; see +.BR socket (7). +.PP +The IPv6 API aims to be mostly compatible with the +.BR ip (7) +v4 API. Only differences are described in this man page. +.PP +To bind an +.I AF_INET6 +socket to any process the local address should be copied from the +.B in6addr_any +variable which has +.I in6_addr +type. +In static initializations +.B IN6ADDR_ANY_INIT +may also be used, which expands to a constant expression. +Both of them are in network order. +.PP +The IPv6 loopback address (::1) is available in the global +.B in6addr_loopback +variable. For initializations +.B IN6ADDR_LOOPBACK_INIT +should be used. +.PP +IPv4 connections can be handled with the v6 API by using the v4-mapped-on-v6 +address type; thus a program only needs only to support this API type to +support both protocols. This is handled transparently by the address +handling functions in libc. +.PP +IPv4 and IPv6 share the local port space. When you get an IPv4 connection +or packet to a IPv6 socket its source address will be mapped to v6 and it'll +be mapped to v6. +.SH "ADDRESS FORMAT" +.sp +.RS +.nf +.ta 4n 5n 20n +struct sockaddr_in6 { + u_int16_t sin6_family; /* AF_INET6 */ + u_int16_t sin6_port; /* port number */ + u_int32_t sin6_flowinfo; /* IPv6 flow information */ + struct in6_addr sin6_addr; /* IPv6 address */ + u_int32_t sin6_scope_id; /* Scope id (new in 2.4) */ +}; + +struct in6_addr { + unsigned char s6_addr[16]; /* IPv6 address */ +}; +.ta +.fi +.RE +.sp +.B sin6_family +is always set to +.B AF_INET6; +.B sin6_port +is the protocol port (see +.B sin_port +in +.BR ip (7)); +.B sin6_flowinfo +is the IPv6 flow identifier; +.B sin6_addr +is the 128bit IPv6 address. +.B sin6_scope_id +is an id of depending of on the scope of the address. It is new in Linux 2.4. +Linux only supports it for link scope addresses, in that case +.I sin6_scope_id +contains the interface index (see +.BR netdevice (7)) +.PP +IPv6 supports several address types: unicast to address a single +host, multicast to address a group of hosts, anycast to address the nearest +member of a group of hosts (not implemented in Linux), IPv4-on-IPv6 to +address a IPv4 host, and other reserved address types. +.PP +The address notation for IPv6 is a group of 16 2 digit hexadecimal numbers, +separated with a ':'. '::' stands for a string of 0 bits. Special addresses +are ::1 for loopback and ::FFFF:<IPv4 address> for IPv4-mapped-on-IPv6. +.PP +The port space of IPv6 is shared with IPv4. +.SH "SOCKET OPTIONS" +IPv6 supports some protocol specific socket options that can be set with +.BR setsockopt (2) +and read with +.BR getsockopt (2). +The socket option level for IPv6 is +.BR IPPROTO_IPV6 . +A boolean integer flag is zero when it is false, otherwise true. +.TP +.B IPV6_UNICAST_HOPS +Set the unicast hop limit for the socket. Argument is an pointer to an +integer. \-1 in the value means use the route default, otherwise it should be +between 0 and 255. +.TP +.B IPV6_MULTICAST_HOPS +Set the multicast hop limit for the socket. Argument is a pointer to an +integer. \-1 in the value means use the route default, otherwise it should be +between 0 and 255. +.TP +.B IPV6_MULTICAST_IF +Set the device for outgoing multicast packets on the socket. +This is only allowed +for +.I SOCK_DGRAM +and +.I SOCK_RAW +socket. +The argument is an pointer to an interface index (see +.BR netdevice (7)) +in an integer. +.TP +.B IPV6_ADDRFORM +Turn an +.I AF_INET6 +socket into a socket of a different address family. Only +.I AF_INET +is currently supported for that. It is only allowed for IPv6 sockets +that are connected and bound to a v4-mapped-on-v6 address. The argument +is a pointer to a integer containing +.B AF_INET. +This is useful to pass v4-mapped sockets as filedescriptors to programs that +don't know how to deal with the IPv6 API. +.TP +.B IPV6_PKTINFO +Set delivery of the +.B IPV6_PKTINFO +control message on incoming datagrams. Only allowed for +.B SOCK_DGRAM +or +.B SOCK_RAW +sockets. Argument is a pointer to a boolean value in an integer. +.TP +.nh +.B IPV6_RTHDR, IPV6_AUTHHDR, IPV6_DSTOPS, IPV6_HOPOPTS, IPV6_FLOWINFO, IPV6_HOPLIMIT +.hy +Set delivery of control messages for incoming datagrams containing extension +headers from the received packet. +.I IPV6_RTHDR +delivers the routing header, +.I IPV6_AUTHHDR +delivers the authentication header, +.I IPV6_DSTOPTS +delivers the destination options, +.I IPV6_HOPOPTS +delivers the hop options, +.I IPV6_FLOWINFO +delivers an integer containing the flow id, +.I IPV6_HOPLIMIT +delivers an integer containing the hop count of the packet. +The control messages have the same type as the socket option. All these +header options can also be set for outgoing packets +by putting the appropriate control message into the control buffer of +.BR sendmsg (2). +Only allowed for +.B SOCK_DGRAM +or +.B SOCK_RAW +sockets. Argument is a pointer to a boolean value. +.TP +.B IPV6_MULTICAST_LOOP +Control whether the socket sees multicast packets that is has send itself. +Argument is a pointer to boolean. +.TP +.B IPV6_ADD_MEMBERSHIP, IPV6_DROP_MEMBERSHIP +Control membership in multicast groups. Argument is a pointer to a +.B struct ipv6_mreq +structure. +.TP +.B IPV6_MTU +Set the MTU to be used for the socket. The MTU is limited by the device +MTU or the path mtu when path mtu discovery is enabled. +Argument is a pointer to integer. +.TP +.B IPV6_MTU_DISCOVER +Control path mtu discovery on the socket. See +.I IP_MTU_DISCOVER +in +.BR ip (7) +for details. +.TP +.B IPV6_RECVERR +Control receiving of asynchronous error options. See +.I IP_RECVERR +in +.BR ip (7) +for details. +Argument is a pointer to boolean. +.TP +.B IPV6_ROUTER_ALERT +Pass all forwarded packets containing an router alert option to this socket. +Only allowed for datagram sockets and for root. Argument is a pointer to +boolean. +.\" FLOWLABEL_MGR, FLOWINFO_SEND +.SH VERSIONS +The older +.I libinet6 +libc5 based IPv6 API implementation for Linux is not described here +and may vary in details. +.PP +Linux 2.4 will break binary compatibility for the sockaddr_in6 for 64bit +hosts by changing the alignment of +.I in6_addr +and adding an additional +.I sin6_scope_id +field. The kernel interfaces stay compatible, but a program including +sockaddr_in6 or in6_addr into other structures may not be. This is not +a problem for 32bit hosts like i386. +.PP +The +.B sin6_flowinfo +field is new in Linux 2.4. It is transparently passed/read by the kernel +when the passed address length contains it. Some programs that pass a +longer address buffer and then check the outgoing address length may break. +.SH "PORTING NOTES" +The +.B sockaddr_in6 +structure is bigger than the generic +.B sockaddr. +Programs that assume that all address types can be stored safely in a +.B struct sockaddr +need to be changed to use +.B struct sockaddr_storage +for that instead. +.SH BUGS +The IPv6 extended API as in RFC2292 is currently only partly implemented; +although the 2.2 kernel has near complete support for receiving options, +the macros for generating IPv6 options are missing in glibc 2.1. +.PP +IPSec support for EH and AH headers is missing. +.PP +Flow label management is not complete and not documented here. +.PP +This man page is not complete. +.SH "SEE ALSO" +.BR cmsg (3), +.BR ip (7) +.PP +RFC2553: IPv6 BASIC API. Linux tries to be compliant to this. +.PP +RFC2460: IPv6 specification. |