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IP addresses can be blocked by administrators in the same way as registered users are. IP blocks can be more powerful and effective, but also have additional ramifications.


Block lengthsEdit

Blocks should be based on the protection of Wikipedia rather than the punishment of offenders. Most IP addresses should not be blocked more than a few hours, since the malicious user will probably move on by the time the block expires. If there is persistent disruption or vandalism from an IP address, the block should be extended (with the 'anon-only' option selected) as long as is necessary to prevent further disruption.

However, IP addresses should almost never be indefinitely blocked. Many IPs are dynamically assigned and change frequently from one person to the next, and even static IP addresses are periodically re-assigned or have different users. In extreme cases, consider long-term blocks over a period of months or years instead. Long-term blocks should never be used for isolated incidents.

If you do indefinitely block an IP address, please place {{indefblockedip}} or {{open proxy}} (do not substitute) on its user or user talk page for tracking purposes.

Shared IPsEdit

Before implementing a long-term block on an IP address with a long history of vandalism, please check if it is shared by performing a WHOIS and Reverse DNS lookup query on the IP to determine if it belongs to a school or a proxy server. If a Shared IP's talk page is not already identified or tagged as such, use either the {{SharedIP}}, {{SharedIPEDU}}, or any one of the templates at Category:Shared IP header templates to do so. For anonymous-only blocks of Shared IPs, please consider using {{anonblock}} or {{schoolblock}} as your blocking reason.

Range blocksEdit

Template:Shortcut Administrators can block ranges of IP addresses (commonly called rangeblocking). Use careful judgement and make them as brief as possible; this can affect over sixty-five thousand IP addresses, potentially affecting millions of users. These should be reserved as an absolute last resort.

If you propose to block a significant range, or for a significant time, consider asking a user with checkuser access to check for collateral blocks - that is, for the presence of other users who may be unintentionally affected by the range block.

Problems and solutionsEdit

Shared and dynamic IP addressesEdit

Many users operate from shared IP addresses, often those belonging to proxies used by large networks or ISP's. Since it is impossible to distinguish between individual users operating from shared IP addresses, blocking one may affect a very large number of legitimate users (ranging up to millions). Users operating from dynamic IP addresses change IP addresses periodically. This can compound the autoblock problem, particularly when they are also shared, because a block targeted at a malicious user may shift to a legitimate user while the target shifts to an unblocked IP address.

Open proxiesEdit

Open proxies may be blocked on sight according to the policy on open proxies. This may affect millions of users in rare cases; however, the IP should not be unblocked until it has been closed. Because even the IPs of open proxies will eventually be reassigned, blocks should not be indefinite, but should be very long term. A year to 5 years is recommended.