Help:Range blocks/IPv6/zh

對於段封鎖的主頁和IPv4的段封鎖，請參閱Help:段封鎖. 就像是IPv4，IPv6的段封鎖由$wgBlockCIDRLimit限制，預設最大允許為/19的段封鎖.

技術說明
IPv6位址的長度為128位元. IPv6位址中的每個位數有16種不同的值（從0到15），每個位數表示了4位元（1 nibble）的值，總共有32位數. 如同IPv4，CIDR表示法以共同前綴來表示範圍. 例如2001:db8::/32表示該範圍的前32位元的二進制位數為00100000000000010000110110111000. 也如同IPv4，MediaWiki使用CIDR表示法來實作IPv6段封鎖.

附帶損害
要評估IPv6段封鎖的附帶損害，最佳指引是檢查WHOIS和該段實際的活躍度. MediaWiki supports looking up a range's contributions with Special:Contributions, e.g. Special:Contributions/2001:db8::/32 (note that the latter range will not return any edits).

In assessing collateral damage it is important to understand IPv6 address allocations to end-users. The most important fact to know about is that single or multiple /64 subnets for an end-user connection is a practical requirement of IPv6. What this means is that IPv6 connections will have at least 264 addresses assigned to them, which is around 18 billion billion; sometimes they can have considerably more. The reason IPv6 requires /64 subnetting is that any deviation from this breaks a great number of IPv6 protocols, and it will also be needed for future developments. The only exception to longer than /64 subnetting is for certain connections where many IPv6 features are not needed, for example a /126 subnet for point-to-point inter-router linking. But this is not relevant for IPv6 rangeblocking since no end-users will have addresses of this sort.

So in many ways IPv6 /64 rangeblocks are akin to blocks of single IPv4 addresses, as a /64 subnet is the norm for connections, although sometimes end-user allocations will include multiple /64 subnets. So generally speaking IPv6 /64 rangeblocks are recommended, as blocks of single IPv6 addresses can be easily circumvented by users with minimal technical knowledge, and normally the risk of collateral damage is low. But be aware that like in IPv4, where a single static IPv4 address may supply a household or institution of some kind, a static IPv6 /64 range may also supply a household or institution, so multiple users can be affected by /64 rangeblocks.

An exception to this is mobile broadband access; these IPs are allocated dynamically within certain ranges, and blocking these are unlikely to be successful, as they are easily circumvented and risk collateral damage; this applies to all types of blocks, whether they are IPv4 or IPv6 blocks of single addresses or ranges. Mobile broadband addresses can be checked using a WHOIS service. Note that IPv6 /64 ranges are unlikely to be a dynamic, rather they are likely to be static, and typically wont change for an end-user. This is due to the large number of available IPv6 addresses, meaning dynamic allocation is unnecessary; this lowers the risk of collateral damage.

How to calculate an IPv6 CIDR range
Although similar principles also apply to IPv4, the fact that hexadecimal digits correspond to exactly one nibble (4 bits) each simplifies the calculation somewhat.
 * 1) Find the common prefix – that is, the string of digits shared by all of your addresses.
 * 2) Expand the common prefix completely (including redundant zeros), and multiply the total number of digits by 4 - that's the size of your common prefix.
 * 3) Use the table below, and add the specified number to your prefix size (this is your CIDR suffix, the number of bits common to all addresses in the range). Append the specified digit to the common prefix you found above. Complete the group of four digits with zeros if necessary.
 * 4) The CIDR is then [common prefix (with additional digit as specified by table below, followed by zeros as necessary to keep the group of four digits complete)]/[common prefix length (plus 1,2, or 3 as specified by the table below)].

Prefix modification table
Example: If your prefix is 2001:db8:abcd:: (completely expanded to 2001:0db8:abcd::), and you have addresses like 2001:db8:abcd:9000:abe:: and 2001:db8:abcd:a000::, you'd use the entry saying that the digits after your prefix match 8-b, append 8 to the prefix, and add 2 to your common prefix's size. This would generate 2001:db8:abcd:8000::/50.

Range table
The color-coding is approximate, and there will be overlaps.

Keys

Tools

 * ip-range-calc
 * NativeForeigner's IP range calculator
 * IP Subnetting and CIDR Calculator
 * Template:IP range calculator
 * IPv6 Subnet Calculator