Manual:$wgSysopRangeBans

This feature was removed completely in version 1.18.0.

Access: $wgSysopRangeBans
Allow sysops to ban IP ranges
Introduced in version:	1.2.0
Deprecated in version:	1.17.0
Removed in version:	1.18.0 (r86125)
Allowed values:	(boolean)
Default value:	`true` (1.4.1-1.17) `false` (1.2-1.4.0)
Other settings: Alphabetical \| By function

Details

Allow sysops to ban IP ranges.

To disable rangeblocking in later versions of MediaWiki, add the following to your LocalSettings.php :

$wgBlockCIDRLimit = array( 'IPv4' => 32, 'IPv6' => 128 );