Help:Range blocks

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 " " in LocalSettings.php.

How to block ranges
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 " " or IPv6 " "). The CIDR affix is the number of starting digits every IP address in the range have in common when written in binary.

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

As the CIDR affix increases, the block affects less 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, or manually calculate the range:
 * 1) Convert the first and last IP addresses in the range to binary.
 * 2) Place both IP addresses one atop the other, and count how many starting digits are exactly alike. This is the CIDR affix.
 * 3) 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

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.