MediaWiki Administrator's Handbook/Block
Block prevents the user of a certain account or IP address from editing for a determined period of time.
When to block 
Blocking policy varies from project to project, but it generally applies to the following categories of user:
- Persistent vandals
- Open or anonymous proxies
- Threats or harassment
- Persistently adding copyright violations
- Inappropriate user names
- Expiry sets a time after which the block is automatically lifted by the MediaWiki software. The dropbox offers several frequently-used time periods, such as "24 hours", "1 week", and "1 month". (Please see note below about block lengths.)
- Block anonymous users only allows users from a blocked IP address to edit using a registered account, only restricting the edits of anonymous users. (This option is not available when blocking a registered username.)
- Prevent account creation prevents the creation of new accounts from a blocked IP
- Automatically block the last IP address used by this user, and any subsequent addresses they try to edit from blocks any IP used by this account
In order to unblock an account (to allow editing or increase the period of the block) go to Special:Ipblocklist where the option is available.
Length of block 
The priority must be to minimise damage to the wiki. However when there is time or on review afterwards some or all of the following may be helpful in looking at the length of the block.
- User contributions. Bear in mind that if a page is deleted it will not be in the contributions. (This is often the case with spam bot type pages.)
- Block log history. This may give guidance on previous blocks.
- WHOIS data
- User talk page on Wikipedia. Given the level of traffic on WP compared to other Wiki's this may have useful history of both editing patterns and warnings.
- Block log on Wikipedia. Again this may give guidance on level of nuisance and block period.
- Check out the spam database on DNS Stuff. If one or more of the lines are red this is an indication of a lack of security of the IP and the likelihood spam may originate from it.
- Ask around! It's always worth it.
Conflicting block lengths 
If a particular user or IP is blocked more than once simultaneously, the MediaWiki software will honor the block that expires the soonest. (This may or may not be the shortest block.) In this case, the sysops who placed the blocks should contact each other and decide which length is most appropriate under the circumstances.
Indefinite blocks 
The "indefinite" option in the Expiry field allows a sysop to block a particular user or IP without specifying an expiration. This block is effectively permanent, but it can be lifted at any time by any sysop. Indefinite blocks should be used sparingly on IP addresses because IPs tend to shift from user to user over time.
Custom block lengths 
The "other" option in the Expiry field allows a sysop to define either a custom block length or a precise date and time when the user or IP will be able to edit again. Custom values must be entered in the GNU date input format.
Range blocks 
The MediaWiki software allows sysops to block entire ranges of IP addresses. Using CIDR notation, enter an IP range between /16 and /31 (inclusive; MediaWiki does not support blocking larger ranges). If you are unfamiliar with CIDR and binary arithmetic, then you should not block ranges.
A properly-applied range block will remove editing privileges from all persons who connect from an IP in the affected range. As a result, it may unintentionally block valued contributors, so it may be worthwhile to consult a checkuser before applying a range block.
Range blocks are a drastic measure, and should only be used for brief periods as a last resort. Poorly-applied range blocks can shut out entire nations!
- Commons -- Commons:Blocking policy
- Meta --
- Wikibooks -- Wikibooks:Blocking policy
- Wikinews -- Wikinews:Blocking policy
- Wikipedia -- Wikipedia:Blocking policy
- Wikiquote -- Wikiquote:Blocking policy
- Wikisource -- Wikisource:Blocking policy
- Wikispecies --
- Wikiversity -- Wikiversity:Blocking policy
- Wiktionary -- Wiktionary:Blocking policy