Manual:$wgEditPageFrameOptions

This variable determines the   header to send on pages sensitive to clickjacking attacks, such as edit pages. This prevents those pages from being displayed in a frame or iframe. The options are:


 * Do not allow framing. This is recommended for most wikis.
 * Do not allow framing. This is recommended for most wikis.


 * Allow framing by pages on the same domain. This can be used to allow framing within a trusted domain.  This is insecure if there is a page on the same domain which allows framing of arbitrary URLs.
 * Allow framing by pages on the same domain. This can be used to allow framing within a trusted domain.  This is insecure if there is a page on the same domain which allows framing of arbitrary URLs.


 * Allow all framing. This opens up the wiki to XSS attacks and thus full compromise of local user accounts.  Private wikis behind a corporate firewall are especially vulnerable.  This is not recommended.
 * Allow all framing. This opens up the wiki to XSS attacks and thus full compromise of local user accounts.  Private wikis behind a corporate firewall are especially vulnerable.  This is not recommended.