Manual:Block and unblock
Sysops can block and unblock IP addresses (and registered user accounts if username blocking is enabled) from editing, uploading files, moving pages, and, if they have been granted such rights, protecting/unprotecting and deleting/undeleting pages. It is important to remember that blocks are preventative, rather than punitive.
- Specify the IP address or user to be blocked. Enter the IP address to be blocked, or the name of the registered user account to be blocked, in the "User" field of the form. Note that nonexistent usernames can also be blocked, so be certain you have the correct username. You can also block a range of IP addresses; see range blocks for instructions.
- Specify a duration for the block. You can select a predefined duration from the drop down box labelled "Expiry", or you can enter a custom value, using the GNU standard format, in the "Other time" field. If the duration given is "indefinite", then the block will not expire, although the IP address or user account may still be unblocked by a sysop.
- Specify a reason for the block (optional). This reason will be displayed to the blocked user if they attempt to edit a page.
Note that in addition to manually entering the IP address or user account to be blocked into Special:Blockip, you may also follow the "Block this user" link from the toolbox in the sidebar when viewing the "User" or "User talk" page of the IP address or user account. You can also click on the "block" link next following an IP address or user account name in the recent changes list.
Blocking options 
|MediaWiki version:||≥ 1.8|
Several extra blocking options were added in version 1.8 of MediaWiki, which are enabled by checking a check box on the blocking form.
- Block anonymous users only (also called softblocking)
- This option changes the effect of a block when blocking an IP address. When it is enabled, the block will only affect anonymous users editing from that IP address; registered users editing from that IP address will not be affected. The option has no effect on a block of a registered user, but does on an autoblock caused by it.
- Block account creation
- This option changes the effect of a block when blocking a user or an IP address. When it is enabled, the registration of new user accounts from that IP address will be disabled while the block is in effect.
- Automatically block the last IP address used by this user, and any subsequent addresses they try to edit from (also called hardblocking)
- This option changes the effect of a block when blocking a registered user account. When it is enabled, the IP address most recently used by the account, and any IP addresses that the account subsequently attempts to edit from will be automatically blocked.
An IP address or registered user account can be unblocked via the list of active blocks. Find the IP address or registered user account you wish to unblock in the list (you can enter the address or name in the "search" field to help you find the entry), and click the "Unblock" link displayed to the right of the block's expiry time.
This will lead you to a confirmation page. Enter the reason for unblocking (optional) in the "reason" field, and click "unblock this address" to remove the block. All unblockings are recorded in the block log.
Note that if a range is blocked, then the unblock must cover the whole range to be effective. Attempting to unblock an individual IP address in the range will not be effective.
Effects of being blocked 
Blocked users may still read pages, but they may not create, edit or move pages, or upload files. Users with certain other user rights will not be able to use those rights when they are blocked; for example, users with the rights to delete and undelete or protect and unprotect pages will not be able to do so when they are blocked. However, users with the rights to block and unblock users will still be able to do so when they are blocked, including any blocks on their own account.
Users who are blocked and attempt to edit a page (or move a page, or upload a file) will see the "user is blocked" message informing them that they have been blocked.
If the autoblock option has been enabled with respect to a block, and the blocked user attempts to edit (or move a page, or upload a file), the IP address being used by that user will also be blocked.
The configuration options below can be set in LocalSettings.php and can be used to enable or disable certain aspects of the blocking interface.
$wgSysopUserBanscontrols the ability for sysops to block usernames. This is true by default. If a sysop tries to block a registered user account and this setting is not enabled, then an error message will be displayed, informing the sysop that the "IP Address does not exist".
$wgSysopRangeBanscontrols the ability for sysops to block ranges of IP address. This is true by default.
$wgAutoblockExpirycontrols how many seconds need to pass until a block on an "autoblocked" IP address will expire. The default is 86400 seconds, which is the same as 24 hours (one day)
$wgBlockAllowsUTEditcontrols whether or not a blocked user is able to edit their own user talk page. This is false by default. The ability to disable the ability of a blocked user to edit their own user talk page, when this variable is true, is an option available in Special:Block.
$wgSysopEmailBansand the blockemail user right control the ability for sysops to prevent users from using the Special:EmailUser interface.
$wgSysopEmailBansis true by default.
$wgBlockDisablesLogincontrols if blocked users will be allowed to login. This is false by default.
- The hideuser user right controls the ability for sysops to prevent a blocked user from appearing in the block log, the active block list, and the user list.
MediaWiki: pages 
- MediaWiki:Ipboptions contains a list of suggested block durations.
URL parameters 
|MediaWiki version:||≥ 1.18|
Special:Block accepts some URL parameters to prepopulate the HTML form:
wpTarget- username/IP address
wpExpiry- expiry time
wpAutoBlock- autoblock setting (=1 or =0)
wpHardBlock- hard block setting (=1 or =0)
wpCreateAccount- prevent account creation (=1 or =0)
wpReason- reason, from selection of MediaWiki:Ipbreason-dropdown
wpReason-other- prepopulating "other reason" text field