Difference between revisions of "Help:Range blocks"

Latest revision as of 21:37, 12 January 2010

Range blocks are technical restrictions applied through Special:Blockip to a group of IP addresses that prevent them from editing, creating new accounts, sending email through the wiki interface, et cetera. Registered accounts editing from these IP addresses will also be blocked, unless you check the box to only block anonymous editors.

Range blocking is enabled on all Wikimedia wikis; to enable it on other wikis, add "{{ #ifeq:

 www.gps.alaska.edu

| www.mediawiki.org | $wgSysopRangeBans | $wgSysopRangeBans }} = true;" in {{ #ifeq:

 www.gps.alaska.edu

| www.mediawiki.org | LocalSettings.php | LocalSettings.php }}.

To block an IP range from Special:Blockip, enter the first IP address in the range followed by a forward slash and a Classless inter-domain routing (CIDR) suffix. You should avoid performing range blocks unless you understand what you are doing, or you may end up blocking tens of thousands of people who are not the problem!

Technical explanation

CIDR notation is written as the IP address, a slash, and the CIDR affix (for example, the IPv4 "10.2.3.41/24" or IPv6 "a3:b:c1:d:e:f:1:21/24"). The CIDR affix is the number of starting digits every IP address in the range have in common when written in binary.

For example: "10.10.1.32" is binary "00001010.00001010.00000001.00100000", so 10.10.1.32/27 will match the first 27 digits ("00001010.00001010.00000001.00100000"). The IP addresses 10.10.1.32–10.10.1.63, when converted to binary, all have the same 27 first digits and will be blocked if 10.10.1.32/27 is blocked.

As the CIDR affix increases, the block affects fewer IP addresses (see table of example ranges). CIDR affixes are not the same for IPv4 addresses as they are for IPv6 addresses.

Calculating the CIDR affix

You can use the table of sample ranges below to guess the range, use a computer script, or manually calculate the range.

Conversion to binary

The first step in manually calculating a range is to convert the first and last IP address to binary representation. (This assumes you're not using a computer script, which can probably calculate the range for you anyway.) An IP address is composed of four groups of eight ones and zeros. Each group represents a number from 0 to 255. To convert a number to binary, you can use a reference table or know the value of each binary digit:

Proceeding from left to right, fill in '1' if the number is at least that value, and subtract that value (if it's not, fill in '0' and don't subtract). For example, to calculate 240:

1. 240 is at least 128, so place 1 and subtract 128.
2. 112 (240-128) is at least 64, so place 1 and subtract 64.
3. 48 (112-64) is at least 32, so place 1 and subtract 32.
4. 16 (48-32) is at least 16, so place 1 and subtract 16.
5. Since the remaining value is zero, all the remaining places are '0'.

Thus, 240 is 1111 0000 because it can be represented as 128+64+32+16+0+0+0+0.

Calculate range

1. Place both IP addresses one atop the other, and count how many starting digits are exactly alike. This is the CIDR affix.
2. Double-check! Being off by one digit could extend your block by thousands of addresses.

The example below calculates the CIDR range between 69.208.0.0 and 69.208.0.255. Note that this is a simple example; some groups of IP addresses do not so neatly fit CIDR affixes, and need multiple different-sized blocks to block the exact range.

IP addresses:
  69.208.0.0
  69.208.0.255
 
Convert to binary:
  0100 0101.1101 0000.0000 0000.0000 0000
  0100 0101.1101 0000.0000 0000.1111 1111
 
Count identical first numbers:
  0100 0101.1101 0000.0000 0000.0000 0000
  0100 0101.1101 0000.0000 0000.1111 1111
  |____________________________|
            24 digits
  
CIDR range:
  69.208.0.0/24

</pre>

Table of sample ranges

The table below shows the IP blocks each CIDR suffix affects. Note that MediaWiki only supports blocking CIDR suffixes 16–32.

References

• Classless Inter-Domain Routing

External links

• IP Address Ranges Block gives you complete IP ranges for certain countries.
• Netmask calculator which helps in making the correct decision for range blocks.
• Rangeblock-Calculator gives you the range you should use when blocking.

Template

Syntax

{{Languages|PageName}}

• PageName (optional) - the name of the page to display language links for. If omitted then the English version of the current page is used. This parameter can normally be omitted, as it is only required if you want to link to a page other than the one you place the template on, which is very uncommon. If this parameter is used on a sub-page make sure you supply the root name, not the full page name (e.g. on MediaWiki/fr you would need to use {{Languages|MediaWiki}} and not {{Languages|MediaWiki/fr}}).

Usage

The template should only be placed on pages that exist in more than one language, and it should be placed in the same location on each translation of the page.

The English version of a page is always the main version, with all other languages as sub-pages, named using the appropriate language code (see below).

For example, on the Main Page you would include the text {{Languages}}, both on Main Page itself, and on each of its language sub-pages. The template automatically creates links to any language sub-pages that exist, e.g. Main Page/ja<tt>, <tt>Main Page/fr, and ignores non-existant languages.

See Project:Language policy for further details about translating pages.

Supported languages

This shows you the name of each language's sub-page (using Main Page as an example). Other languages may be added easily as necessary. Please use the appropriate prefix, as used on Wikipedia when adding a new language. Please do not add languages for which no pages exist yet, as this will increase the time needed to include the template without adding any benefit (languages are only displayed to the user when the relevant page exists).

The link on the language names goes to the Wikipedia in that language. If no Wikipedia in your language exists, do not add pages in that language to MediaWiki.org! This wiki is not the place for language advocacy - please go through the correct channels, and once your language has a Wikipedia then please return to add content here.

Example

Here is how the language bar looks on the MediaWiki page: Template loop detected: Template:Languages