Manual:$wgShowIPinHeader

User accounts, authentication: $wgShowIPinHeader
Show the IP in the user bar for anonymous users.
Introduced in version:pre 1.1.0
Removed in version:1.27.0 (Gerrit change 239649; git #ea335eb5)
Allowed values:(boolean)
Default value:true

Details edit

Show personal tool links (links to user page and user talk page) for anonymous visitors ("IPs"). Disabling this allows for improved caching, because all anonymous visitors can then be served the exact same version of each page.

If $wgUseFileCache is enabled, setting $wgShowIPinHeader to true does not have any effect. Instead, it is automatically set to false at runtime.