README.IPv6

$OpenBSD: README.IPv6,v 1.3 2008/12/03 15:43:17 sthen Exp $

IPv6 support for the OpenBSD httpd(8)

To support IPv6 the apache module API/ABI had to be changed, to avoid
IPv4-dependent structure member variables (like use of u_long to hold
an IPv4 address, or whatever).  Keep this in mind when writing new
modules or adding modules to the ports collection.

Basically you can write IPv6 address where IPv4 address fits.

extra command-line argument:
	-4	Assume IPv4 address on ambiguous directives (default)
	-6	Assume IPv6 address on ambiguous directives
	-U	Don't assume a specific address family on ambiguous
		directives

	The above options can be used, for example, to disambiguate
	"BindAddress *".

base commands:
    Listen
	Listen is expanded to take one or two arguments.
		Listen port
		Listen address:port
		Listen address port
	This is to let you specify "Listen :: 80", since "Listen :::80"
	won't work.

mod_access:
    deny from
    allow from
	"deny from" and "allow from" supports IPv6 addresses, under the
	following forms:
		{deny,allow} from v6addr
		{deny,allow} from v6addr/v6mask
		{deny,allow} from v6addr/prefixlen
	Also, wildcard ("*") and string hostname matches IPv6 hosts as well.

mod_proxy:
    ProxyRequests on
	http/ftp proxying for both IPv4 and IPv6 is possible.
	Access control functions (NoProxy) are not updated yet.

	NOTE: for security reasons, we recommend you to filter out
	outsider's access to your proxy, by directives like below:
		<Directory proxy:*>
		order deny,allow
		deny from all
		allow from 10.0.0.0/8
		allow from 3ffe:9999:8888:7777::/64
		</Directory>

virtual host:
	If you would like to this feature, you must describe 'Listen'
	part on configuration file explicitly. like below:
		Listen :: 80
		Listen 0.0.0.0 80

    NameVirtualHost
	NameVirtualHost is expanded to take one more two arguments.
		NameVirtualHost address
		NameVirtualHost address:port
		NameVirtualHost address port
	This is to let you specify IPv6 address into address part.

	Note that, if a colon is found in the specified address string,
	the code will to resolve the address in the following way:
	1. try to resolve as address:port (most of IPv6 address fails)
	2. if (1) is failed, try to resolve as address only
	If there's ambiguity, i.e. 3ffe:0501::1:2, the address may not be
	parsed as you expect (3ffe:0501::1 with port 2, or 3ffe:0501::1:2
	with default port).  To get the right effect you are encouraged
	to specify it without ambiguity.  In IPv6 case "address port"
	(specify address and port separated by a space) is the safest way.

    <VirtualHost host:port [host:port ...]>
	If you would like to specify IPv6 numeric address in host part,
	use bracketed format like below:
		<VirtualHost [::1]:80>
	Note: Now we DO NOT handle old non-bracketed format, 
		<VirtualHost 0:0:0:0:0:0:0:1:80>
	      so configuration file must be updated.
	Note: The following is bad example to specify host ::1 port 80.
	      This will treated as host ::1:80.
		<VirtualHost ::1:80>

logresolve (src/support)
	error statistics in nameserver cache code is omitted.

mod_unique_id
	Originally mod_unique_id used IPv4 address as a seed for UNIQUE_ID,
	and took IPv4 address registered onto DNS for the hostname (UNIX
	hostname taken by gethostname(3)).  Therefore, this does not work
	for IPv6-only hosts as they do not have IPv4 address for them.

	Now, UNIQUE_ID can be generated using IPv6 address.  IPv6 address can
	be used as the seed for UNIQUE_ID.
	Because of this, UNIQUE_ID will be longer than normal apache.  This
	may cause problem with some of the CGI scripts.
	The preference of the addresses is based on the order returned
	by getaddrinfo().  If your getaddrinfo() returns IPv4 address, IPv4
	adderss will be used as a seed.
	Note that some of IPv6 addresses are "scoped"; If you happened to use
	link-local or site-local address as a seed, the UNIQUE_ID may not be
	worldwide unique.

	If longer UNIQUE_ID causes a problem, define SHORT_UNIQUE_ID in
	mod_unique_id.c.  In this case, length of UNIQUE_ID will be kept the
	same.  However, for IPv6 addresses mod_unique_id.c will use the last
	32bit (not the whole 128bit) as the seed.  Therefore, there can be
	collision in UNIQUE_ID.

	The behavior should be improved in the near future; we welcome your
	inputs.

configuration file
	We do not support IPv4 mapped addresses (IPv6 address format like
	::ffff:10.1.1.1) in configuration file. 

Credit:

This file is derived from the README.v6 file that accompanied the
original patchkit for Apache 1.3.9 from the KAME project.  It was
written by Jun-ichiro itojun Hagino.

	 http://www.kame.net/
	 mailto:core@kame.net